The Arisaka Tailcap Adapter allows Streamlight Protac Rail Mount 1 and 2 lights to use Surefire Scout tailcaps and remote switches. 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.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 a removable buffer o-ring on the front face which ensures the battery cannot move rearward while firing.NoteCompatible light include Protac Rail Mount 1 and Streamlight Protac Rail Mount 2. Compatible with 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 with Surefire ST07, SR07, SR-D-IT, and TNVC/Unity TAPS remotes.