The WFM was the result of the first time we answered a government RFP. They needed a product that would allow the user to attach a flashlight with 17 mm to 26 mm in circumfrences to the Picatinny Rail. With in a week of submitting our WFM, the Army was at our door and telling us they loved the idea and design...Since 2001, we have delivered over 200,000 units to the military and thousands more to civilian users. No tools required, 3.5 oz, can use with gloves, inexpensive, and nearly indestructible.