The PDI W-Hold (50 Degree) hop rubbers are soft and tight with external ribs to push against the hop chamber. 
They fit snugly on virtually all AEP barrels to create an excellent seal. 
The softer Nitrile material performs superbly at low temperatures and remains grippy enough to float medium/heavy weight ammo. 
 
The internal mount is split to allow the BBs to be kept perfectly centrally to create a much more consistent and even backspin. 
The lips are an excellent shape and work with the vast majority of AEP hop chambers. This is our go-to hop rubber for all AEPs and CMGs.
 
Also compatible with the TM NGRS MP5 and NGRS Mk46.