EISCO 12pc Cylindrical Bars Density ID Set – Hardwood, Softwood, Aluminum, Copper, Brass, Rubber, Nylon, Derlin, PVC, Glass, Acrylic & Teflon – Includes Storage Block – Study Density & Mass. Materials included: Hardwood, Softwood, Aluminum, Copper, Brass, Rubber, Nylon, Derlin, PVC, Glass, Acrylic & Teflon.