48.4mm (1.5" /40mm) to 50mm Imperial to Metric Pipe Adapter

Metric to Imperial Pressure Pipe Adapter. 

48.4mm OD spigot on one end (40mm/1.5" pressure pipe diameter - any standard 40mm/1.5" fitting sleeves over this end. 
x
50mm ID socket (50mm Metric European/UK pressure pipe diameter).

1.5" / 40mm pressure pipe has an OD of 48.4mm
50mm METRIC pipe has an OD of 50.0mm

In Australia, there are a small number of spas and baths imported with metric plumbing. This adapter allows an easy pipe size change to the common pipe size used in Australia. Generally referred to as 40mm in size, its identical to USA 1.5" pressure pipe and fittings.