This polyurethane dumbbell is made of alloy steel that is completely pressed into each solid steel head and welded onto the outside for maximum strength. This avoids damage and any needed secondary maintenance. This fixed weight dumbbell is covenant because you do not need to spend the time to place them back into the holder. You do not need to worry about them being loose and you can exercise more stably and safely. The heads are wrapped with a polyurethane layer of 8mm, are shock absorbent, and impact resistant. It better protects the floor and surrounding equipment.There is a medium level knurling design on the surface of the grip that improves grip and comfort. Even if the palms of your hands are sweaty during exercise, you can still firmly hold these dumbbells. The dumbbell’s hard chrome treatment is not only beautiful but also corrosion resistant. They are durable and a good choice for commercial or household use.