This is an optional Exotek TC6 Aluminum Spring Perch Set. Machined, polished and factory blue anodized alloy spring perch sets for the TC6.2, TC6.1 and TC6. Extra milling for a lightweight design but reinforced strength and of quality cnc cut aluminum. Milled holes also help reduce debris from collecting inside. 13.25mm inside diamter for perfect alignment and fit with standard springs sets.