Arisaka Defense Tailcap Adapter Streamlight Protac Rail Mount HL-X Black. In particular the Protac Rail Mount lights can now be used with the Surefire SR-D-IT and TNVC/Unity TAPS dual switches which are commonly paired with laser/illuminators like the ATPIAL and DBAL series. One of the main flaws of the Protac Rail Mount lights is also addressed: Streamlight did not design a front battery spring into the light so under recoil the battery can come off the front contact and cause the light to flicker or blink. To help prevent this behavior the adapter includes two different o-rings (one for CR123 cells one for 18650 cells) which can be placed on the back end of the battery before screwing on the adapter. The o-ring ensures the battery cannot move rearward while firing. Specifications for Arisaka Defense Streamlight Protac HL-X Tailcap Adapters: Manufacturer: Arisaka Defense Color: Black Fabric/Material: 6061-T6 Aluminum Finish: MIL-A-8625 Type III Hard Coat Anodized Length: 0.49 in Quantity: 1 Weight: 0.6 oz Flashlight Model: Streamlight HL-X Condition: New Mount Type: Rail Diameter: 1.04 in Country of Origin: USA Features of Arisaka Defense Streamlight Protac HL-X Tailcap Adapters Compatible lights: Streamlight Protac Rail Mount HL-X Compatible tailcaps: Surefire UE (Newest version with black ring where the remote plugs in. The old gray ring version is not compatible) Surefire DS Surefire Z68 Compatible Remotes (with Surefire UE or DS tailcap): Surefire ST07 Surefire SR07 Surefire SR-D-IT Unity TAPS Unity Hot Button Modlite Modbutton Modlite Modbutton Lite (Surefire plug) Package Contents: Arisaka Defense Streamlight Protac HL-X Tailcap Adapters Arisaka Defense TA-RMHLX: Tailcap Adapter Streamlight Protac Rail Mount HL-X Black