15mm x 10mm Brass Compression Reducing Coupling (Known as 15mm Copper Pipe Fittings/Brass reducing Coupling/Compression Coupling Also Available in 8mm, 10mm, 12mm, 15mm, 22mm, 28mm)

Flomasta Brass Compression Reducing Lead to Copper Coupler 7lb 1" x 15mm - Screwfix

Duraplast UK™ 22mm - 15mm Brass Compression Reducer | Reducing Coupler Pipe Connectors for Copper Pipe | Reducing Coupling | 1 Pack | No Soldering Required | Leak-Free & Durable