The item in the image is an Oase replacement nut and sealing set

It is designed for use with Oase UVC pond clarifiers, such as the Vitronic and BioPress models

The set includes a retaining nut, O-ring seals, and a clamping screw to secure the quartz sleeve. 

These components are essential for maintaining a watertight seal and protecting the UV lamp inside the filter unit. 

Genuine Oase spare parts ensure optimal functionality and pond water clarity