Vktech&reg; 4Pcs Black Plastic Upright Piano Caster Cups Pads Floor Carpet Protector Solid and durable caster cups, set of 4pcs Perfect to your piano to protect the carpet or hardwood floors from the scratches, damage, and holes that the metal casters on upright pianos can cause. These could also be used for other large heavy items like safes as long as the feet of the item fit into the inner diameter. Material: Hard plastic