Compression tee 22mm x 22mm x 15mm.
15mm on the branch.
Brass fitting, made to the European EN1254 standard.
Compression plumbing fittings do not require heat or solder. The joint is formed by tightening a nut and compressing the olive (included with fitting) onto a pipe, which forms the seal. They can be used on wet pipework, and are suitable for hot and cold systems.