Based on this product's specifications, here are some alternatives and similar models
Compression ring 15 mm brass for plumbing fittings Conex E--1020065--
Summary description:
Brass compression ring 15 mm by Conex (model E--1020065--) for use with compression fittings in plumbing systems. Manufactured from brass for corrosion resistance and mechanical strength, it provides a sealing and gripping interface between pipe and fitting. Suited for 15 mm copper or compatible plumbing tubes, useful in water supply and central heating installations and repair work.