Classic Army M15 Hopup Chamber.

Classic Army Metal Hopup Unit for Classic Army M4/M16 series. Also works well with all metal body upgrades from various manufacturers. Even works with stock Marui M4 and M16 style airsoft rifles with some modification.

Classic Army MP5 (P065M Type) Hopup Chamber for replacement or repair of existing hopup units.  Can be used to replace any TM/Classic Army compatible MP5.*Note: Not compatible with new B&T eries MP5's from Classic Army.

G&P 1pc Metal Hop Up Chamber for M4/M16 G&P Hop Up Bucking included 

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.

The first mass production LED module for Hopup is now here from Madbull.  Designed to be used with the Madbull Ultimate Hopup unit, you can change your Hopup chamber to be a tracer unit easily.

SRC replacement hopup bucking and spacer

Hopup bucking replacement for AEG airsoft rifles. Include hop bucking and brass barrel sleeve.

Replacement hopup unit for UTG Shadow Ops Sniper Rifle and the TSD SD96 Sniper Rifle.  Includes Hopup unit and Hopup Bucking.  *note: Hop adjust screw not included.

Classic Army, G36 hopup chamber