Piano Caster Cups Grand Piano Caster Cups Wood coasters Cups Piano Caster Pads for Grand Piano Made High Quality Duty 100% Hardwood Material Designed for use with grand pianos Designed to be placed under a piano's legs in order to protect floors and carpets Underside of Each Cup is Lined With Felt Pad, Have Sound-Proof -Antiskid- Vibration free chassis Effect Protects Wood and Carpet From Caster Damage Each cup mat is made of 100% hardwood, every part of the tree stem will have different colors, each cup mat is a little off color, this belongs to the normal.