 32 of the fittings are themselves spring-loaded mechanisms, actuated during capture and rigidization by corresponding components of the ACBM.The primary CBM/CBM seal is also part of the PCBM, as are preloaded stand-off/push-off springs to stabilize its relative motion when the CBM/CBM joint is nearly mated.Two types were specified for the PCBM, differring only in the durability of their seal.