The Arisaka Tailcap Adapter offers a crucial enhancement for Streamlight Protac rail-mount 1 and 2 lights by enabling compatibility with Surefire Scout tailcaps and remote switches. This adaptation extends the functionality of Protac rail-mount lights to utilize Surefire SR-D-IT and Unity Axon dual switches, commonly paired with laser/illuminators such as the ATPIAL and DBAL series. A notable improvement addressed by this adapter concerns the inherent issue in Protac rail-mount lights: the absence of a front battery spring. This omission can lead to the battery dislodging from the front contact during recoil, causing erratic behavior such as flickering or blinking of the light. To mitigate this problem, the adapter includes a removable buffer O-ring on the front face. This O-ring serves to secure the battery in place, preventing it from shifting rearward under recoil and thus maintaining consistent contact and reliable performance during use.