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Foursevens Quark Smart QSL



I’ve been involved with LED flashlights since about 2010 – roughly six years.  I’ve owned many and reviewed more of them then I can count here on ThruMyLens.  There are two types of LED flashlights which interest me – Tactical (for use in combination with a firearm for defensive purposes in low light encounters) and Every Day Carry (a light which is small enough to be carried on your person and has multiple settings for a variety of illumination tasks.  For the purposes of this discussion, I’ll call a Tactical Light one that has a true tactical user interface, which is a tail switch that has “instant on” capability.  Press the tail switch, and the light comes on at full strength.  Release, and the light turns off – a single, simple mode of operation.  In my experience, many LED lights advertise themselves to be “tactical” when in fact they are less than ideal to use in conjunction with a firearm.  In order to maximize sales, manufactures will typically add modes of operation and additional functions which are handy, but can get you killed in a gun fight where you have to use a flashlight.  The Surefire Fury P2X is an excellent example of a light with a purely tactical interface.  It’s a light that I can bet my life on.  EDC lights are actually easier to get right, but so many manufacturers get these wrong too.  Often times, useful modes of operation on some EDC lights can require the user to perform difficult to memorize and execute twists of a flashlight head or button taps in order to get to the desired mode of operation.  In other cases the user has to sequentially wade though every mode the light has until the desired mode is found.  Yuck.  So finding either a good Tactical Light or a good EDC Light is no simple task.  But a light that can function well in both roles?  In the six years I’ve been following the industry, I’ve not seen a light that perform well in both tactical and EDC roles.  Until now.  Foursevens has finally done what no other manufacturer I know of could with the introduction of the Quark Smart QSL….and so much more.  But we’ll get to that later.  Right now, let’s look at the form factor and basic functions.

The Quark Smart QSL is a single CR123 sized light with a CREE XM-L2 emitter ( 85 cri ) with the following specifications per the Foursevens website:

Dimensions Length: 3.43 in / Diameter: 0.86 in / Weight: 1.46 oz
LED Emitter CREE XM-L2
Voltage range 2V-4.2V
Spot Beam Angle: 29.2 Degrees / Diameter at 3 meters: 780 mm
Flood Beam Angle: 62.8 Degree / Diameter at 3 meters: 3.7 meters
Brightness Levels Moonlight: 1 lumens, 15 days / Low: 10 lumens, 18 hrs / Medium: 100 lumens, 3 hrs / High: 350 lumens, 1.5 hrs
Special Modes Strobe: 3 hrs / SOS: 5 hrs / Beacon(hi): 10 hrs / Beacon(lo): 30 hrs
Reflector Textured
Body Material Type-III hard-anodized aircraft-grade aluminum
Bezel Material Type-III hard-anodized aircraft-grade aluminum
Lens Material Optical-grade glass lens, sapphire coating, antireflective coating
Included Accessories Battery, lanyard, split ring for keychain attachment, spare o-ring, holster, finger-grip

For my purposes, the size is perfect – a near match for my previous favorite EDC flashlight, the Sunwayman V11R:


The side activation switch is illuminated and has both a red and a green lighting element – both are used at different times by the light to communicate difference messages to the user.  When activated, the green element lights up the switch, and when turned off the green light will pulse at regular intervals to help locate the Quark Smart QSL in the dark.  The tail switch on the Quark Smart QSL can and does function like a true tactical “deadman switch” which I’m overjoyed about.  Better yet, the light will tail stand, which is a key requirement for me for any EDC light that I would consider.


The button on the side of the Quark Smart QSL’s body can be depressed to turn on the light, and depressed again to turn it back off.  Quick double taps will cycle you through the various flashlight modes.  I was initially concerned that, given the Quark Smart QSL’s size, it might be easy to activate the side button while activating the tactical tail switch.  However, after using the light, I’d say it’s at best a remote possibility that this could happen because 1)it’s easy to rotate the light in your hand so you’re not touching the side activation switch and 2.  The side activation switch actually takes a bit of effort to press – it’s not something you’ll unintentionally brush by and have the light come on.

Now, I’ll be honest – I could stop right here, and the Quark Smart QSL would already be a light I’d whole -heatedly recommend.     But there’s more!  A lot more as it turns out.  The Quark Smart QSL has “smart” in its name because the light can, via Bluetooth, connect wirelessly to to a smartphone.   Using an app developed by Foursevens (currently available on Apple iOS and soon to come to Google Android) you can operate the light, program various functions and modes, and take advantage of extended functionality no other light on the market has as of this writing!  Here’s a screen capture of the iOS version of the Foursevens app:


I’ll attempt to explain what the Foursevens app is currently capable of doing.  Keep in mind the app has, of this writing, only been out for a few weeks, and it’s constantly being updated.  For a discussion regarding the various settings and functions available, refer the numbers in the following screen capture:


  1.  The majority of this area is taken up with the battery level indicator.  Yes, the flashlight has the ability to monitor the battery some information about the remaining power levels.  The app can even be set to alert you if the remaining power drops below a pre-defined level (I have mine set to 20%).  There’s also a an on/off toggle in the upper left hand corner, and a temperature gauge for the flashlight’s internal circuitry in the upper right.
  2. The main functionality is the middle area is the ability to switch between the pre-programmed interfaces.  Right now, it appears as though “Tactical” and “Pro” are the only two interfaces available.  The main difference between them seems to be in how the output of the Quark Smart QSL is handled relative to the tail switch activation.  In “tactical” mode, the power output of the light when the tail switch is depressed is determined by the last mode in which the flashlight was in when operating via the side activation switch.  Conversely, the “Pro” interface allows you to “fire and forget” relative to the tail switch output.  Once you’ve cycled through and selected an output via tail switch double taps, that output will be constant when the tail switch is activated, and is not impacted by switching output modes with the side activation switch.  Ironically, the “Pro” interface is the more tactically beneficial of the two available modes, but neither is tactically ideal.  In “Tactical Mode” the tail switch activation should be predictable (it does the same thing every time) and should be alterable by any method or sequence of activating the tail switch.  The “Pro” interface is more predictable than the “Tactical” interface, but the fact that an accidental double tap of the tail switch while trying to activate it could put the light into a different output mode makes it unsafe for true tactical use.  It would be better that the behavior of the tail switch ONLY be alterable from the Foursevens app, and not by any of the controls on the light itself that could be accidentally done during a stressful, life-or-death situation.  Note there is a grayed out, non-functioning selection below the interface label which says “Instant Access” – one can only assume this functionality will be introduced in a future upgrade of the app.
  3. This area controls the various output modes and their behaviors associated with the interface mode you select from #2.  Note the in the photo above, all the output modes appear blue with the exception of the first mode – “moon” which is white.  This means that, when in the “Pro” interface, when the side activation switch is pressed, “moon” or moonlight mode is the default 1st mode in which the light be when turned on by the side activation switch.  Each of the output modes can toggle in and out of the white “default activation” mode, meaning you can assign any of the output modes to the first one when the light is turned on.   Just tap on any of the modes, and your selection will turn from blue to white, which in turn will turn the mode previously designated as first from white back to blue.  You can also see that two of the output modes have red writing on them.  If you press and hold on any of the output mode icons, the phone will vibrate, and the red writing will appear on that mode.  That mode has been effectively turned off, and taken out of the mode rotation.  So based on the photo above, if I cycled through the available modes on the Quark Smart QSL using the side activation switch, the light would skip “Strobe” and “Beacon Low.”  The days of having to cycle through a maddening number of modes you don’t even use just to get to the one you want are over!

If you scroll on the app, you’ll actually see some additional functions along the bottom of the screen:


The first icon on the left (it looks like it represents the sun or light) and will take you back to the main “battery screen” if you are in the GPS/Map screen (explained below).  The icon on the far right of a flashlight is grayed out, and is also non-responsive/non-functioning.  Again, we can assume the two non-functioning icons will be enabled in the future at some point.  The middle icon looks like a folding map with a pin in it, and when pressed, brings up the last known GPS location of the Quark Smart QSL:


You’ve also got a couple of potentially handy options here.  The first is the green “page device” button – this will cause the flashlight to go into strobe mode.  So if the Quark Smart QSL has rolled under a bed or behind a dresser, this should make finding it easier.  There’s also the “Notify when out of range” toggle switch.  When toggled on, if the Bluetooth connection is broken because you’ve got too far away from the Quark Smart QSL, then the following notification will appear on the iPhone along with a vibration or audible alert:


It’s a typical iOS notification, which means it disappears after just a few seconds, but it is retrievable via the iOS Notification Center:


Not only do you get the iOS notification of the disconnect once your out of range of the light, the light itself will go into strobe mode.  This could be very beneficial if you drop the light or leave it lying somewhere – you won’t get very far without several signals alerting you and those around you of what happened.  In total, the “GPS screen” within the Foursevens app provides three different tools/options that help keep you from losing your Quark Smart QSL, as well as locating it if you do misplace it.  They may not be fool-proof, but their better than what you have on the light you’re using today…or the light you don’t have today because you lost it yesterday…


Nothing made by the hands of man is perfect, so there are a few things about the Foursevens Quark QSL which I’d like to see improved.

Pocket Clip – It is not obvious to me why Foursevens opted to not put a pocket clip on the Quark QSL, but it’s a huge omission.  I’m keeping mine in my back pocket next to my wallet…which is work well enough, but not ideal.  I’m guessing the next gen model will include a pocket clip – I just hope and pray it’s the kind that screws in, not clips on.  I’ve lost two pocket clips and actually had to replace my Sunwayman V11R because of the clip on pocket clip…which is another reason I stopped carrying a flashlight for quite some time.  UPDATE:  Foursevens did reach out to me and let me know that, based on the fact that pocket clip-less Quarks were more popular than those with pocket clips in the previous generation, they decided to make the Quark QSL clip-less.  Can’t make all the people happy all the time I suppose…

No True Moonlight Mode – The Quark Smart QSL has a “moonlight mode” of one lumen, but one lumen is actually quite bright.  Many, such as myself prefer a sub-one lumen moonlight mode.  If the emitter and circuitry can support a sub-one lumen output, then I would assume at some point the app will allow for customized outputs, which gives me hope this one can be addressed in the future.

Despite these shortcomings, the Foursevens Smart QSL is the best, most sophisticated LED flashlight currently on the market and I highly recommend it.  Amazon currently has it in stock for the best price:

The Foursevens Quark Smart QSL on Amazon

In addition to this written photo review of the Foursevens Quark Smart QSL, I’ve recorded a supplementary video review:

About John B. Holbrook, II
John B. Holbrook, II is a freelance writer, photographer, and author of, as well as and *All text and images contained in this web site are the original work of the author, John B. Holbrook, II and are copyright protected. Use of any of the information or images without the permission of the author is prohibited.

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