Plan B Competition mod kit from Plan B Supply Co. is design for competition use and advance users only. It comes with a 24 mm Doc rda and is BF ready. Super simple 2 post design with large post holes for even the biggest of builds. Precision machining for a gorgeous finish. Comes with 810 size Ultem drip tip and a 510 adapter. Gold plated standard 510 pin and bf pin also included.