Sold in a set of 2 ($42.29)  or 4 ($84.57) Solid Brass made by 'Faultless' 

For spinet & console pianos with free standing front legs.

Spinet pianos usually range in height from 36" to 40"

• Wheel Diameter  1-1/4" 
• Wheel Face Width  11/16" 
• Stem Dimension  11/32" diameter x 1-5/8" Long 

Supplied with Plastic Sockets CR-7 - Shown Below

• Length of stem 1-15/16"
• OD: 3/4" At Base, and 1/2" At Top 

All of our wheels are sold with their own sockets. You will be required to replace the entire wheel / socket assembly to ensure a proper fit.
You may be required to modify the existing hole in your piano to accommodate the new casters.
Unfortunately there is no reference manual to tell us what wheels would work in each of the over 12,000 pianos manufactured.