The Shimano BB-RS501 Bottom Bracket Right & Left Adaptors BSA Bearing is a high-quality and reliable solution for upgrading your bike's bottom bracket. These adaptors are designed to fit BSA bottom brackets and come with both right and left options for a complete installation. The durable bearing construction ensures smooth and reliable performance, while the easy installation process makes it convenient for any cyclist to upgrade their bike. Upgrade your bottom bracket with the Shimano BB-RS501 adaptors for a more efficient and enjoyable ride.