Both ends have a male 3/4 inch BSP outer thread. One end has a 1/2 inch BSP female inner thread, the other a (rare) 5/8 inch BSP female inner thread, sometimes found on old bib taps. Use this brass adaptor fitting to allow connection of modern 3/4 inch Hozelock / Gardena type garden hose pipe fittings to the outlet of your older outside tap. .
eBay