Medium Single Arch Fluoride Trays (Upper White, Lower Blue), Package of 100 Trays. Used for bite registrations, fluoration and ortho with clearance. With 4 lb foam to ensure rigidity. Disposable. Results in detailed impressions. Single Arch Fluoride Trays are made of a closed 4 lb density foam for reliable durability and rigidity. The outstanding anatomical depth for the gingival line allows complete fluoride coverage in applications.Available in Upper White and Lower Blue.