"S" laygear. Made for all pre-rod change. 4 synchro gears were the same except for the laygear and 1st motion shaft. The Cooper S and 1275GT had a closer ratio with a 18 teeth 1st motion and 29 teeth (15,20,25,29)  laygear. The 25 teeth were 3" wide whereas the std ratio laygear with same teeth count was 1/8" wider so beware. One of the most sought after 4 synchro remote box close ratio gears. The most certain identification is done be inspecting the laygear. If it is a laygear you have a close ratio box. While you are inspecting the laygear be sure to check the inner surface of the laygear which serves as the outer race of the layshaft bearings. This surface can breakdown resulting in premature failure of both the bearing and the shaft.These have been fitted to Rod change gearboxes with layshaft modifications required when owners required a closer ratio gear set.