MASTER CASTER COMPANY-CASTER,W,2"BL,SFT,BS,4/ST. Superball Casters, 75 lbs./Caster, Vinyl, Black, 4/Set. 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. Dual usage caster features a specially molded ball wheel that provides safe rolling on hard floor surfaces, chair mats and low pile carpeting. HOW TO SELECT CASTERS. Stem Type: W; Wheel Tread: Soft; Color(s): Black; Material(s): Vinyl.