Products › Draft Arm Wrench (Shank / Tower Wrench) Image 1 of 4 Image 2 of 4 Image 3 of 4 Image 4 of 4 Draft Arm Wrench (Shank / Tower Wrench) from $18.00 Shank wrench is specifically designed to tighten the nut on the back of a faucet shank. Size: Select Size Heavy Duty Lightweight Offset Add To Cart Added! Shank wrench is specifically designed to tighten the nut on the back of a faucet shank.