Benchworld’s premium solid wooden or clear acrylic caster cups are the best choice for an upright piano. The outer diameter is about 3.75" and the inside diameter is 1 15/16". Moreover, this item comes in a set of 4 with black adhesive felt. The felt will be easy to slide whereas the rubber makes it harder to slide the piano.

Features

• Size: Small
• Color: polished ebony, polished mahogany, polished walnut, polished white, clear acrylic
• Felt installed under to avoid scratches on your hardwood floor
• Inner Diameter: 1 15/16"
• Outer Diameter: 3.75"
• Excellent for upright pianos
• Set of 4