Darnell Superior quality casters.
Excellent for schools, churches or any facility that moves pianos frequently.
Single Rubber-fibre wheel. Features heavy duty, double ball-bearing swivel. The upper row carries the load weight, and the lower row takes up all the side thrust.

• Wheel Diameter: 2"
• Wheel Face Width: 1"
• Wheel Material: High Capacity Neoprene
• Load Capacity ea: 125 lbs. (375lbs total for Grands or 500 lbs total for Uprights)
• Height Without stem: 3"
• Stem Dimension: 1/2" Dia x 1-1/8" Long

591A - Grand Set of 3 - $155.40

• Supplied with removable, square CP-2C cast-iron sockets with 4 screw holes. (screws not included)
• OD: Of Stem 15/16"
• ID: Of Stem  1/2"
• Height: 1-5/16"
• Screw Space: 1-3/16" Side to Side 
• 1-11/16" On Th Diagonal 
•  Track Plate Thickness: 1/4"

591 - Upright Set of 4 - $183.40

• Supplied with removable, round CP-1C cast-iron sockets with 4 screw holes. (screws not included)
• OD: Of Stem 15/16"
• ID: Of Stem  1/2"
• Height: 1-5/16" 
• Screw Space: 1-3/16" Side to Side
• 1-11/16" On Th 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.