Casters (Set 4)Locking for MJM Height Adjustable Shower Chair Scooter Accessories 16 x 12 x 16 18747 16 x 12 x 16 inches No# 10018 Tip MJM's Exclusive Reinforced Caster System Allows Additional Structural Support To Our Entire Product Line Our Positive Engaging Lock Holds The Wheel Securely So There Is No Swivel Movement When Locked * The Unique Design Allows Easy Movement On Hard Surfaces And Helps Eliminate the Wheel From Falling Into Cracks * Soft Non Marking Tread * (It Will Not Leave Black Marks Or Leave Groves In Wood Or Vinyl) * Quite Mobility * (Hard Treads Make A Lot Of Noise) Non Rust Plastic Body And Wheels * High Load Capacity (160 lbs) Non Slip Tread * Double The Tread Surface For Superior Breaking * Easy Reach Brake Tab * R 3TW 3 TWIN