Locking casters are sold individually. The casters keep your piano from rolling while it should be stationary.
One of my favorite moving devices! The Ground Transporter allows a single person to lift a grand piano in less than one minute! The transporter will move grand pianos from 4-9 ft in length and up to 3,000 Lbs. The unit will fold up for easy storage and movement. The patent pending design is intended to be used to install a piano dolly by sitting atop the piano dolly while raising the piano in order to place the piano onto the dolly wheel base. Excellent tool! Made in USA.