The Arisaka Tailcap Adapter allows Streamlight Protac Rail Mount HL-X lights to use Surefire Scout tailcaps and remote switches. 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.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.Streamlight's TEN-TAP Programming is still fully functional with the use of Surefire tailcaps and remote switches in combination with the Arisaka Tailcap Adapter. The current setting is not altered unless purposefully changed just like using the stoc...