All caps except the slip-fit model have a center hole tapped 8-32 and are equipped with a threaded stem to secure the cap to the riser.
C2L
2" Lotus Cap
Cast brass
2 1/2" OD.
C2SF
2" Slip-fit Cap
Spun & etched brass
2 1/2" OD, slips 1 7/8"
C2R
2" Standard Cap
Spun & etched brass
2 1/2" OD