PTFE ring, 49 mm outside diameter × 38.3 mm inside diameter, belonging to O-ring set 180007-0047 for Hanovia medium-pressure ultraviolet disinfection systems. PTFE is used here rather than an elastomer because this ring sits where the seal is exposed to direct ultraviolet at the sleeve end, and ordinary rubber degrades under that exposure. Available separately for cases where only this component needs renewing rather than the whole set. Reference number 2250-1007.