This three piece set includes a thick vulcanized firm rubber base which absorbs shock, plus a solid steel block which is 15/16" (24mm) thick and 3" (75mm) in diameter. The third piece is a sturdy nylon block the same size that fits into the rubber base for lighter, more delicate work. This is a well made set, and allows one to hammer (for projects such as texturing, hardening and flattening) without creating excess noise and vibration at the bench. The rubber base absorbs some of the "blow" from the hammer. Total weight of set is 2.5 lbs.
If you are going to use this block for metal stamping, you will want to take the steel circle block out of the rubber bottom and just use the steel block flat on your table. Using the rubber base under it will cause a slight bounce when stamping and prevent a strong impression.