Thyrm Switchback On non-Compatible Flashlights

Currently the Thyrm Switchback is compatible with a variety of 1in diameter lights from Nitecore, Klarus, Foursevens, Olight, Elzetta and, of course, Surefire. I decided I didn’t want to limit my other flashlights potential and found a way to make Thrym’s awesome product work with some “non-compatible” flashlights.


Foursevens Quark Smart

My first experiment was with the Foursevens Quark Smart Q2SL-X. I did a little homework and figured out that the Quark Smart’s tail cap/body diameter was very similar to the Surefire backup series lights (.8in range).

Thyrm makes a switchback sized specifically for the Surefire Backup, so I bought one for my Quark Smart. Out of the box the switchback was not compatible. The inside diameter of the switchback was smaller than the outside diameter of the tail cap. The tail cap was also shorter than the length of the switchback.

I decided my best course of action was to friction fit the switchback to the Quark Smart tail cap. So, I carefully used a dremel to make the inside diameter of the switchback larger. I methodically stopped after each minor adjustment to make sure I didn’t open it up too much.


Eventually it got to the point where I could almost force the switchback over the tail cap. Then I used the dremel to take a little off the top and bottom of the switchback so that it was the same height as the tail cap.

At this point I decided I needed to heat up the switchback and the tail cap to ease the fitting process. Using my heat gun, I took a few seconds to heat up the tail cap, then the switchback, and proceeded to push/twist the switchback over the tail cap to the desired spot and….. IT WORKED!

I could remove the switchback if I wanted by repeating the heating/pulling/twisting process, but for all intents and purposes, the switchback was now a permanent part of the flashlight. I did eventually move the switchback further down the body to tailor the light for my wife’s small hands. She just changes the batteries by unscrewing the head of the light instead of the tail cap.


Streamlight Strion

My next experiment was with my department issued Streamlight Strion. This was a little trickier to plan because the switchback is designed to go over the tail cap, but the tail cap on the Strion is very small/short. To make matters more interesting, the inside diameter of the switchback was larger than the light body, but the lip at the bottom (which captures the surefire tailcaps) was smaller.

I needed the switchback to attach to the light body and clear the tail cap so I could still access the battery. I resorted to my previously successful method of custom fitting the switchback, but this time I only opened up the diameter of the lip. Similarly, once I got to the point where I could almost force the lip over the light body, I stopped. This time, I removed the tail cap and put a strip of electrical tape over the top of the light body. The strip of electrical was just long enough to overlap on itself a couple centimeters.

Again, using my heat gun, I carefully warmed up the light body/electrical tape, and then the lip of the switchback. Then, with the tail cap removed, I used the edge of a table to push the body of the light into the switchback. The ridges of the light body, combined with the electrical tape, captured the lip of the switchback around the body of the light.

The switchback is free to rotate around the body of the light, but won’t budge when pulled up or pushed down. You can stuff the included O ring between the light body and switchback to get a more “secure” feel.


Fenix PD32

This match up required no changes to be made to the switchback, but did require significant work to be done to the tailcap. Initially I thought the switchback would be compatible without any modification. However, the lip of the switchback was too thick and prevented the tail cap spring from making contact with the battery. I tried various sizes/amounts of aluminium foil between the spring and battery without success.

An important part of the effectiveness of the switchback is getting the right distance between the ring and the button of the flashlight. If the two are too close, your light will point at your target’s feet. If they are too far, the light will go over your target’s head. With the Fenix, I decided the best way to get an ideal distance between the two was to put the switchback over the body of the light, rather than the tail cap.


I removed the included pocket clip and unscrewed the head, allowing me to pull the switchback over the body of the light towards the tail cap. Then, I wrapped electrical tape around the tailcap/body three times before repeating the heat and push/twist process to get the switchback over the tailcap. This prevented the use of the pocket clip as intended, but effectively secured the switchback to the light and its integrated pocket clip works just fine.

Out of the box, the tail cap of the PD32 has two large shrouds or protective fins. They aid in preventing negligent discharge of the light and also allow it to tail stand. In this particular case they were a nuisance because I couldn’t effectively access the button while using the switchback. So, those got filed down until my access to the button was unhindered aaaaand … Voila! In retrospect, I should have kept the fins somewhat elevated rather than filed all the way down – I occasionally press too hard and activate the constant on unintentionally.


Streamlight Protac 1AA Dual

I didn’t do this one personally, so I can’t be as specific on the details. However, my friend described the process as being very similar to the Fenix – filing/dremeling down the fins/shrouds and friction fitting the switchback onto the tail cap. After playing around with this combo the only downside I found was removing the tailcap to change batteries. Certainly not impossible, but it helps to have pliers.

Other Lights to Come

I’ve since contacted Thyrm to inquire about upcoming changes, if any, to allow the switchback to be compatible with a wider variety of lights. Andrew Frazier, the genius behind the product, got back to me and assured me that a Gen 2 is in development and that Thyrm is working hard to include the Strion and other streamlight flashlights to their list. In the meantime, if you have these lights or very similar ones, these solutions may help.


Author: SPFSolutionz

I’m just a ginger who has an interest in self defense – hence SPF solutions (sun protection factor) OR (Self-Protection-Focused). I don’t consider myself an expert teacher, but I try to be an expert learner and as such, draw from expert instruction I've received and my personal experiences and practice to share what I know. I spent six years as an infantry marine and am currently a full time police officer, conceal carry advocate, and family man.

2 thoughts on “Thyrm Switchback On non-Compatible Flashlights”

  1. SPF, thanks for sharing. I found this article because I hope to install a Switchback on a foursevens light as well. Do you know if you used the Backup Tactical (Momentary) or the Backup Click Switchback on your Q2SL-X


    1. Awesome. I can’t remember for certain, but I believe I got the backup momentary because my foursevens has a momentary tail cap as well. You should be able to use either one though. I’ve since put a backup on an eagletac dx30. Also, Thyrm has hinted at a new/updated switchback on Instagram, which will hopefully be easier to attach to “non compatible” lights.


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