ZCL M4 / M16 CNC ROTARY HOP UNIT by ZC LEOPARD

High quality made from CNC machined aluminium, comes with all the fittings.  Out of all the Chinese made Prowin / Rotary style chamber this one easily has the best fitment, although please make sure rotary style hop chambers are fully compatible with your AEG. 

I recommend using a tiny amount of silicon grease on the wheel where it meets the oring.