Tri W-G - Tri W-G Treatment Table Accessories, Caster : Set of 4 casters that can be added to the legs of Tri W-G Hi-Lo Treatment Tables. Casters are exclusive to Tri W-G products. Each of the casters are 3.5" tall and are easy to install. They enable clinicians to easily roll treatment tables between rooms. The casters can be locked for stability during treatments. These casters are accessories for all three Tri W-G treatment table models.