Locking Rod End Caps are used on almost all systems with locking. They are used at the end of the locking rod.
20mm Reinforced End Cap - SL60, SL70, WD66, WA67, HSW (newer models)
20mm Standard End Cap - SL60, SL70, HSW (older models)
15mm End Cap - SL35, SL45, WD65, SL50