The Arisaka Defense Tailcap Adapter is designed to allow Streamlight Protac Rail Mount HL-X lights to use Surefire Scout tailcaps and remote switches. This adapter is not compatible with the Protac 2.0 Rail Mount Lights or the Rail Mount HL-X Laser model.
To operate, the adapter requires the use of a Surefire UE or DS tailcap, which is not included. This compatibility opens up the Protac Rail Mount lights to work 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.
A notable limitation of the Protac Rail Mount lights is that Streamlight did not design a front battery spring into the light. Under recoil, the battery can come off the front contact and cause the light to flicker or blink. The Arisaka adapter addresses this issue by including two different o-rings—one for CR123 cells and one for 18650 cells. These o-rings can be placed on the back end of the battery before screwing on the adapter to ensure the battery cannot move rearward while firing.
