Designed with an extended shank shaft for total adjust-ability. If you frame is adjustable than your want you oarlock to be the same. No matter how tall you are or what your rowing from, you should be able to set these oarlocks at the ideal height. Comes with spacer kit. Includes three spacers (1/2″ , 1″, & 2″). This allows for lots of options so you can be dialed in.