The Shimano Tiagra R451 Dual Pivot Brake Caliper is designed for bicycles with mudguard fitting. The caliper has a 57mm arm and Super SLR dual pivot design keeping friction to a minimum, improving braking performance. Enhanced brake arch proportions give a quicker linear response and increased power. Specification Material: aluminium Designed for use with ST-4600, ST-4603, ST-5700, ST-5703, ST-6700 or ST-7900 STIs for correct leverage ratio Toe-in adjustable brake shoes Size: FRONT, REAR; Colour: BLACK, SILVER These great value 57mm drop Shimano brake calipers are designed for frames with larger clearances, allowing enough room for full length mudguards and making them perfect for winter and training bikes. The Super SLR dual pivot design allows for superior braking performance with the aluminium lever arms running on coated pivot washers for a smooth, friction free response. Setup is easy thanks to toe in adjustable brake shoes and the resin QR thumb lever allows for fast wheel removal.