The Bullgear hop-up unit is the number one upgrade for M60 and PKM compatible airsoft guns. The Bullgear hop-up unit's hop-up lever is radically different from the original presser. In the Bullgear, the presser is in a horizontal position, just like in most other electric guns. The Bullgear hop-up unit corrects the problems caused by the original presser being in a vertical position and enables accurate and smooth threading of the bullet in M60/PKM model machine guns.