The Pinhead seatpost lock prevents removal of your seatpost. Once installed, the seatpost lock remains permanently on your bicycle, even when you ride. When you need to adjust your saddle height, your Pinhead key lets you do this quickly and easily. Pinhead locks cannot be removed with tools such as hammers, pliers, picks, universal socket tools, grinders or bolt cutters. Our convex disc technology prevents your parts from being removed by bike thieves. Our locks use a special coded key. The key is ergonomically engineered to install and tighten your locks, and also serves as a bottle opener. Each key is different, and comes engraved with a nine-digit code so it can be replaced by Pinhead if lost.