Product Name: Office Chair Caster Wheels
GUARANTEED NOT TO DAMAGE FLOORS - Encased with soft, smooth polyurethane, our casters are safe to use on hardwood, carpet, tile, and more without leaving any scratches or marks. No desk chair mat necessary
Product name: Chair caster
Material: PU
Product Dimensions:6 x 3 x 4.5 inches
Color: Black, white, red, orange etc
Stem size:7/16" diameter 7/8" length
http://fr.zinhardware.com/