O-ring, 37.47 mm inside diameter × 5.33 mm section, part 130027-0038-01, for Hanovia medium-pressure ultraviolet disinfection systems; also catalogued against reference 2203. Those dimensions correspond to the standard imperial size AS568-325 (1.475 in inside diameter, 0.210 in section), which is given here so the seal can be identified or sourced generically in an emergency — though for water-contact and UV-exposed positions the material specification matters as much as the size, and the Hanovia part is the correct item for planned work. Reference number 2241-0607.