This Yamaha adjustable chair is constructed of 100% hardwood, and adjusts in height from 17" to 21.5". The seat of the piano chair measures 15.5" X 16.5". The padded insert measures 12" x 11.5".

A piano chair is a great option for those who spend hours practicing at the piano. The back support provided by the chair allows for comfortable practice, while the sloped black puts the musician in the correct posture position. The seat of the piano chair has a padded vinyl top.
The Adjustable Piano Chair with Wood Back is engineered to support up to 350 pounds, offering reliable stability for pianists of all sizes.
Easily Adjustable:
This piano chair uses a notch system, making it quick and easy to adjust the height of the bench is small 1/4" increments. As can be seen in the photos above, at the back of the seat, there are two handles--you squeeze them together, which unlocks the mechanism, and allows you to raise of lower the seat (very easy to do, this can be done one handed by people of all ages). Above the two handles is a lever, which which you can push to the left or right. This is a safety mechanism which locks the seat in place, and you have to turn the safety off in order to adjust heights (note the seat will stay in place even if the safety lock isn't engaged, it just keeps someone from bumping it while you're playing).
 
Frame Material: Solid Wood
Seat: Padded, Medium-Density Padding
Color: Black
Finish: Semi glossy
Backrest Type: Fixed Solid Wood 
Product Dimensions: 15.5"L x 16.5"W x 17-21.5"H (39L *42W *43-54.5H cm)
Adjustable Height Range: 17" to 21.5" 43-54.5 cm
Weight: 22lb (10kg)
Adjustment Mechanism: Notch-Release 
Professional refurbished
Imported from Japan