Positive and negative teeth design makes it stable and not easy to drop chains prevents sand accumulation. Widen and thicken corner angle design makes it easily forced and not easy to break. CNC machining and hollow out design makes it lightweight. It is constructed of aluminum alloy material. A set includes different styles. It's suitable for bike. Item Name: Fold Bike Chainring Material: Aluminum Alloy Features: Wear-resistant, CNC Craftsmanship, Lightweight Size Details: Crank Size: 25cm x 20cm x 4cm/9.85" x 7.88" x 1.58" (Approx.) Crank Chainring Size: 30cm x 30cm x 4cm/11.82" x 11.82" x 1.58" (Approx.) BCD: 13cm/5.12" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: Style A/B/C: 1 x Crank 5 x Screws or Style D/E/F: 1 x Crank 5 x Screws 1 x Chainring