This tool allows you to hold the pinion flange when loosening or tightening the pinion nut on Mazda Miata 1.8 differentials. Once the driveshaft is removed, position the 3 bolts onto the the pinion flange, secure with the supplied nuts and loosen/tighten the large pinion nut. Works on 1.8 liter Mazda Miata's with open or Torsen differentials. Does not fit 1.6 Miata's.