Every racer needs to be able to check bolt stretch. These gauges are for checking your rod bolts.
(left) This gauge is adjustable and registers on the bottom pin with a dial indicator on top. Check your bolt before you run the rod set, check it after you torque it one time, and these will be your references if you want to check the rod bolts after a full pass. $79.95
(middle) This gauge is basically the same as the first one except the frame is billet and it has a bottom adjusting screw as well. $89.95
(right) This gauge is a very simple gauge. You just drop the bolt in the hole in the end and read the difference between the new reading and a reading after a run. $59.95