While BB30 and PF30 bottom brackets share the same critical outer width and internal bearing dimensions, the outer diameter is 46mm on the PF30 bottom bracket sleeves compared to the 42mm OD on the BB30 bottom bracket. So if you have a BB30 frame, you'll need this specific adapter to install your Campagnolo Ultra-Torque crankset. The adapter consists of two black anodized aluminum cups that press into the PF30 shell. Once installed, the Campy Ultra-Torque crankarms with integral bearings may be slid into place and bolted together. Note: We strongly recommend a shop quality headset press and properly sized mandrels be used to install the adapter cups. Be sure to install the adapter with the groove on the drive side, and don't forget to install the wire clip.