We don't recommend using after market bolts for mounting our bags. Other bolt head shapes may interfere with the mounting system. If you need different length bolts than what came with your bags for any reason, you can purchase them here. If you are running a custom setup on your bike, we recommend that you contact us so that we can ensure compatibility. 5/16" diameter bolts will fit sportster models, all other models use 3/8" bolts. Sold as a pack of 4.