Sultan - Topex Single Arch Fluoride Tray 100/Pk LargeColor coded with arch ID for easy identification and placement White upper tray includes U on handle, blue lower trays include L on handle Deep distal dam, prevents fluoride overflow, eliminates gagging and ingestion Topex? Single Arch Disposable Fluoride Trays have detailed occlusal anatomy on the biting surface, which forces fluoride gel to contact interproximal regions for total vertical coverage.