Replacement hop unit for M4 style AEG's. An alternative design using a larger dial for adjusting the amount of hop for greater control.

This ZO Rotary One-Piece set is more durable and accurate in feeding BB 
Improves the Firmness of the chamber & stabilizes the muzzle velocity 
Enhanced Hop-Up Bucking for Accuracy. 
Also, fit tightly to the barrel base to keep the chamber being centered 

Includes all parts needed for installation