The Weltool BB18 body and TC20 tail cap set is designed for the weapon light head. The BB18 allows the use of 1 18650 or 2 CR123A batteries (depending on the voltage requirements of the light head), the TC20 tail cover has a full power output forward switch, and has a low internal resistance phosphor bronze spring that can handle 10A current .

This set is compatible with Weltool LH series heads, including LH1, LH2, LH3, LH5, LH6, LH8, LH9,LH10, LH18, etc. It is also compatible with surefire M600DF heads: