Jagwire Pro LR2-E Ebike Disc Brake Rotor MagnetJagwire LR2 E eBike Disc Brake Rotors feature an integrated magnet for use with E bike speed sensors. 2 piece design features an aluminum spider and a separate stainless steel brake track Stainless steel machined braking surface resists corrosion and is tuned to reduce braking noise Aluminum spider features an integrated concentric ring and reinforced rivet joints to resist warping and improve durability For rear wheel use on E bikes with dropout