The Arisaka Momentary Tailcap is a replacement switch for the Arisaka 300 and 600 Series Light Bodies, plus Surefire Scout and E-Series lights. This model is designed to be momentary only with twist for constant on. The tailcap can be threaded all the way in for constant on, or backed out approximately two turns to prevent accidental activation during storage or travel.
The Arisaka Tailcap is CNC machined from 6061 aluminum and MIL-A-8625 Type III hard coat anodized. Made in the USA.
I purchased this tailcap to put on a Surefire E-Series flashlight. The original Surefire black momentary tailcap (Z54) is almost impossible to acquire. This tailcap is a perfect fit and functions flawlessly. The contact spring could be a little thicker IMO but otherwise a well made product. A momentary interface is a must for true tactical applications when using a flashlight in conjunction with a firearm. SKD had it in stock and shipped it ASAP. I would definitely order from them again.