15mm (Half inch) black steel fittings. These are half inch BSTP threaded 15mm internal for 22mm outside diameter plumbing pipe fittings and plumbing pipe lengths in Black Steel finish threaded as 1/2″ BSTP. Finish with diluted Raw Linseed Oil to make rubbed iron furniture and decorator components.
This is a pipe and fitting that is now referred to by a metric size name 15mm