Kimax® culture dishes have reinforced beaded edges to resist mechanical breakage and to help in centering the bottom inside the cover. Dishes remain clear after repeated use in wet or dry sterilization cycles. Covers have a fused-on bright red ceramic enamel marking spot and inscription, including "Cover"; bottoms have a white ceramic enamel inscription, including "Bottom". The combination of different colors and wording permits quick and easy identification of the parts when sorting, selecting and assembling pairs. Bottom also has a vertical arrow on the side to precisely locate serial dilution starting points. Shelf-packs contain twelve covers and twelve bottoms, which are packed in separate boxes. Designed from Federal Specification NNN-D-1478.