Rated 5 out of 5Â by Elscripto Sizing
This is a fitting reducer. The big end fits into a 28mm fitting (elbow, tee etc), a 22mm pipe fits into the small end. If you want to join a 22mm pipe directly to a 28mm pipe in a straight line, you need a reducing coupling.
Rated 2 out of 5Â by R10JCS Beware sizing
This product is not made to convert 28mm to 22mm pipework in the normal way i.e. pipe slots into the fitting. The 22 mm end is like this but the 28mm end fits inside the pipe which if cleaning the pipe internally to get a good joint is difficult can be problematic.