Heat-treated steel center wrapped in hot-cast polyurethane Eliminates rebound to reduce fatigue during use Non-sparking, non-marring material reduces surface damage Polyurethane exterior resists chemical damage and corrosion Virtually unbreakable construction A.M. Leonard Dead-Blow Hammers feature a single-piece, heat-treated steel centered encased a hot-cast polyurethane. Unlike cheaper, plastic models, the faces of our hammers are convex and have extra material around its faces. Steel shot within the head creates a dead blow effect when impacting a surface. These hammers increase your overall strike force up to 40 percent while the non-sparking, non-marring surface minimizes damage to surfaces. Proudly made in the USA!