Thin Flange Bottom Bracket Socket Pro Kit These sockets are designed to create a tight grip on thin flange bottom brackets to avoid slipping while torquing cups into bike frames. These single-sided sockets are used for installing and removing 48.5mm 16-notch, 52mm 16-notch and 50mm 12-notch bottom bracket cups. The sockets have a machined 3/8" drive, which can be used to allow 3/8" drive torque wrenches to be attached and threaded onto 1/2 inch UNC press rod for secure and easy installation of thin flanged bottom brackets. Machined 6061 Aluminum Anodized Red Kit includes: (1) 1/2" UNC Threaded Rod (1) 1/2" Adjustable Press Stop (1)6806/29 Bearing Drift (1)6806 Bearing Drift (1) 24x37 Bearing Drift (1) Wheels MFG Thin Flange Bottom Bracket Socket for 48.5mm 16-notch pattern. (1) SRAM Thin Flange T47 Bottom Bracket Socket for 52mm 16-notch pattern. (1) Praxis Thin Flange T47 Bottom Bracket Socket for 50mm 12-notch pattern.