Feature:1. HIGH HARDNESS: Bike Chainring is made of aluminum alloy, which is much harder than the original steel sprocket.2. HIGH ACCURACY: The 104BCD sprocket adapter adopts aluminum alloy CNC cutting to ensure the accuracy of product use.3. HIGH PERFORMANCE: This round sprocket adapter effectively the bikes from scratches, prolongs wear life.4. PORTABLE: The Bikes Chainring is lightweight, durable, easy to carry and easy to install. The is easy to .5. COMPATIBLE: 104BCD conversion base is perfect, compatible with Bafang electric bike mid drive motor BBS01 BBS02.Specification:Item Type: 104BCD Sprocket AdapterMaterial: Aluminum AlloyBCD: Approx. 104mm/4.1inSize: Approx. 74mm/2.9inFits: 7 8 9 10 11 Speeds Package List:1 x 104BCD Sprocket AdapterNote:Please allow some errors due to manual measurement.