Diamond Hop Up Rubber 50° for AEG The Diamond hop-up seal has an internal diamond-shaped support that provides extra range.

The amount of degrees of the bucking indicates what muzzle velocity it is suitable for.

50° : Less than 360 fps (1.2 J)
60° : 295 fps - 390 fps (0.8-1.5 J)
70° : 360 fps - 460 fps (1.2-2 J)
75° : 426 fps - 490 fps (1.7-2.25J)
80° : over 490 fps (2.25 J)