Additional top bracing on larger sizesfor maximum strength.Melamine tops have a harder and smoother writing surface than real wood furnitureand about the same water and scratch resistance. They will give years of service with proper care..Crayon and permanent marker can be removed without damage. Heavy-duty adjustable height legs with oversize hairpin brace and shouldered set screws for maximum safety. Speedwrench included for fast and secure height adjustments. Chrome inner leg resists scratches. Choice of black (standard) or silver mist legs.Legs adjust from 19" to 29" in 1" increments.Legs attach to top with 6 screws per leg.