Darnell Heavy Duty Casters with Ball Bearings in Wheels.

Dual Rubber-fibre wheels
Darnell dual wheel piano casters are equipped with four sided double ball raceways. **S-STYLE** features ball bearings in the wheels for easier rolling.

Excellent for schools, churches or any facility that moves pianos frequently.

• Wheel Diameter: 2"
• Wheel Face Width: 3/4" Each Wheel
•  Wheel Material: Hard Rubber
• Load Capacity ea: 230 lbs. per wheel  (920 lbs for Uprights)
• Height Without stem: 3"
• Stem Dimension: 1/2" Dia x 1-1/8" Long
• Supplied with removable, round CP-1C cast-iron sockets with 4 screw holes. (screws not included )
• OD: Of Stem15/16"
• ID: Of Stem 1/2"
• Height: 1-5/16" 
• Screw Space: 1-3/16" Side To Side 
• 1-11/16" On The Diagonal
• Track Plate Thickness: 1/4"

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.