* Thin Flange Bottom Bracket Socket Designed to create a tight grip on thin flange bottom bracket to avoid slipping while torquing cups into bike frames.* This single-sided socket is used for installing and removing 48.5mm, 16-notch bottom bracket cups. * The socket has a machined 3/8'' drive, which can be used to allow 3/8'' drive torque wrenches to be attached and locks onto 1/2 inch UNC press rod for secure and easy installation of thin flanged bottom brackets. * Machined 6061 Aluminum Anodized Red