GearWrench 3887 77 Pc. SAE/Metric Ratcheting Tap and Die Set The GearWrench 3887 77 Pc. SAE/Metric Ratcheting Tap and Die Set features the Twist Lock guide system which reduces the ”walk back” of the die guide and keeps the dies centered while cutting. The GearWrench 3887 77 Pc. SAE/Metric Ratcheting Tap and Die Set’s ratcheting T-handles wind dies with a 5° swing arc and have a reversing lever to eliminate hand-over-hand turning.