This pack includes:
2x Rubber buckings.
60 degree rubber is softer than normal 80-90 degree rubber. Much easier to install and operate.
Shark Hop-up Bucking was originally designed to prevent double feeding.
By having 3 special "fins" inside the bucking, Shark Hop-up Bucking can hold one and only one B.B. tightly in the chamber.
Shark blue Hop-up rubber