Conversion base adopts aluminum alloy cutting to ensure the accuracy of product use. Conversion base material is aluminum alloy material, hardness is much higher than the original steel chain wheel, strong and durable It can be used with many accessories for mountain bikes and can be combined with a variety of configuration options Compatible for Bafang Electric bicycle Mid Drive Motor 36V/48V 250W 350W 450W 500W 750W moto XC AM DH multiple routes city commuting. Delivery Quantity: 1 Piece Package Contents: Only the above package contents, excluding other products. Size: 13cm (Reminder: The size is measured manually, please allow 1-2 cm measurement error) Colour: Black (Due to different monitors and lighting effects, the actual color of the item may be slightly different from the color shown on the picture.)