The Hammer Gloves are an upgrade for Knuckles in Sonic Adventure 2. They are a pair of knuckle duster-like gauntlets that allows Knuckles' Punch Attack, Drill Claw and Spiral Upper to destroy iron craters. Using this upgrade leaves a red energy trail when punching. They are the equivalent to Rouge the Bat's Iron Boots.
The Hammer Gloves can be found inside the Death Chamber. At the beginning of the stage, hit the hour glass in front of you and a door that leads into a hallway should open. Head then into this hallway before the door closes and the Hammer Gloves will be located in the first room on the right after entering the hallway, which entrance is blocked by some wood craters.