The plates of this training dumbell are made of a polymeric composite which makes it highly durable. The center is covered in a soft synthetic winding making it very comfortable for your dog to pickup. The training dumbell plates are removable; With all 4 plates (per side), you have an IPO level 3 dumbell (2000g). With 2 plates (per side) it becomes an IPO level 2 dumbell (1000g). With 1 plate (per side) it's an IPO level 1 dumbell (650g). This is conviently an "all in one" dumbell!