Twenty mm UV quartz cell, part no. UVQC-20(1), Path length=20 mm; Exterior W, L and H=12.5, 22.5 and 45 mm; Interior W and L=10 and 20 mm. Each cell is packaged in an individual plastic case with a PTFE lid. UV quartz cells have a "U-shaped" bottom and the Fluorimeter quartz cells have a "square bottom".