Dental Impression Tray, Solid / Non-Perforated, Lower Arch, Size 3, this structure is defined by its open center loop (U-shape), which is anatomically designed to accommodate the tongue in the lower jaw (mandibular arch). The smooth, non-perforated tray walls rely on a rolled rim-lock edge to secure the impression material mechanically. The stamped number "3" on the flat thumb handle denotes a standard medium size profile for adults.