Cambro Mobile Premium Total Locking Brake Caster, 5 inch Diameter -- 2 per case.Corner Connector Set Corner connectors attach a basic unit to a second unit in a 90 degree angle or between two units to form a U shape. A set of corner connectors are needed for each shelf. When using corner connectors, weight bearing capacity will decrease to 400 lbs. per shelf. Casters A variety of casters are available for mobile or high density units. Donut Bumper 3 1/2" Bumper can be used on mobile Camshelving to protect the shelving if bumped. Dunnage Stand Recommended for heavy usage. Increases weight bearing capacity to 1000 lbs. on the bottom shelf of units 54" or longer. ID Tags Easily clip onto traverses to help identify stored items. Made of PVC. Includes 12 HAACP labels. Available in 3" and 6" length. Seismic Foot Available to bolt a post to the floor for a more stable base in geographic regions where earthquakes can occur or cruise ships. Screws not included. Wall Fastener Available to bolt a post to the floor for a more stable base in geographic regions where earthquakes can occur or cruise ships. Screws not included.