JW Bicycle Products 4 Bolt Sprockets are made in the USA from 7075-T651 aluminum with integrated threaded bosses so you don't have to fumble around with the back nut when tighten the bolts. The threads are M8 x 0.75 so they will work standard chain ring bolts. Fits 104mm 4 bolt pattern spiders. Designed for BMX racing and single speed bikes. Teeth are offset to one side to help with chain alignment when using outboard bearing bottom brackets. Available in 32 - 52 tooth. Bright dipped anodize. Silver, black, blue and red.