These are for soundproofing and earthquake resistance. [Brand] This is a product of AJPT COOPERATION, a reliable brand. [Quantity] Sold as a set of 4. I forgot the list price, but I bought them for about 15,000 yen. [Material and Size] Made of durable rubber, they are circular with a diameter of approximately 15.5 cm. Designed for upright pianos. These are soundproofing insulators for upright pianos. They prevent key-striking noise and vibration. - Brand: AJRT COOPERATION - Quantity: 4 - Material: Rubber, felt on the back - Shape: Circular - Color: Black Maximum diameter: Approximately 15.5 cm Minimum diameter: Approximately 6 cm ■Features Due to its unique structure and material (special natural rubber), it absorbs the vibrational energy generated during piano playing. The sound of the piano escapes to the floor below along with the vibrations through the casters. It has excellent soundproofing effects to prevent sound leakage to the floor below. I bought these about 15 years ago when I moved and have been using them with the same KAWAI piano ever since. I haven't moved them much during that time. I am selling them because I am getting rid of the piano as part of a decluttering effort. There are no problems with their use, but there are many scratches due to aging. Please understand. Upright piano footrests, set of 4 insulators, soundproofing, for upright pianos, footrests Soundproofing and vibration-damping effect, insulators, YAMAHA Scratch-resistant, flooring, street piano