Madbull's Ultimate 3-in-1 Hopup Unit is one of the best hopups currently available!! Alone with all-metal construction, they're also including the popular MadBull blue bucking (60 degree).Features:Including a Tracer LED Unit (Optional, Sold separately), Chamber Lock, and Easy Adjustment Device.(1) The LED Tracer Unit (COMING SOON): You can buy it separately and attached to the Hopup unit.