AccuDent XD Impression Trays are thermoplastic heat moldable trays. By simply placing the trays in hot water the size and shape of the trays can be easily adjusted to accommodate all arch forms. These trays are also disposable one-time use to prevent cross contamination and to meet high OSHA standards. Dentate Tray Assortment: 4 each Upper S,M,L, 4 each Lower S,M,L Edentulous Tray Assortment: 4 each Upper S,M,L, 4 each Lower S,M,L