MADBULL AIRSOFT 60° RUBBER BUCKING WITH NUB. Why 60 Degree? 60 degree rubber is softer than normal 80-90 degree rubber. The softer rubber tends to create a good air seal with the nozzle Softer rubber provides higher friction/grip and makes the hop up effect more pronounced with less velocity loss associated with typical hop up systems where the hard bucking must be pressed deep and hard into the hop up relief cut on the barrel. This causes dramatic reduction in speed How to install: Apply some silicone oil inside and outside the bucking when installing onto the barrel and into hop up chamber. Tech Note: Hop-Up Buckings are wear items and should be changed as often as feasible. And should be replaced when upgrading or anytime the inner barrel is removed from the hop up unit. Small pin holes and tears can occur when removing and reinstating used buckings.