Contemporary design, strength and performance make these replacement casters an excellent choice for office and home furnishings. With appropriate stems and fasteners, each caster can be used on wood, metal and tubular metal chairs, furniture and other equipment. All casters carry the manufacturer's guarantee against defects in material and workmanship. To ensure proper support and safe rolling, neck must fit 1-1/2" diameter chair base so that base and caster fit together as a solid unit. HOW TO SELECT CASTERS:1. Remove caster from leg of chair base. 2. Match the stem of the caster to diagram. Select the correct length and diameter. (Tops of stems can be flat or rounded--either will fit.) 3. Determine if caster is to be used on chair mats, hard floors or carpeting. Choose soft wheel casters for use on chair mats, linoleum (vinyl), and hard floors; hard wheel casters for carpeting.