This caster base fits inside 27" deep WRK Series racks and only increases the overall rack height by 1 . Inner caster base design keeps rack low for stability. Works with LF leveling feet to secure rack in place. Robust steel construction with black powder coat finish. Includes (4) 3" pre-installed non-locking commercial grade swivel casters. 1,300lbs weight capacity. UL Listed in the US and Canada