All plastic, professional grade construction will not rust, chip or peel. Resists dents. Reinforced rims add strength and durability. Built-in handles allow easy, non-slip lifting and anti-jam nesting. Double-ribbed base increases stability and dragging capacity. Gray, white and yellow are USDA Meat & Poultry Equipment Group Listed and assist in complying with HACCP guidelines. Gray, white and yellow are certified to NSF Std. #2 and Std. #21. Strong, snap-on lids are available for secure, stable stacking.