Can anyone tell me the name of the threaded fitments I have connecting
15 mm flexible pipes with a female 1/2 inch BSP end to the female 3/4
inch BSP fittings on a bar thermostatic shower?

Unfortunately my card reader has packed up so I am unable to post a
picture.

This is a fully threaded 2.5 inch long fitting, with a male 1/2" BSP
thread at one end (to connect with the flexible pipe), and a male 3/4"
BSP thread at the other (to connect with the shower fitting). I have
also noticed that the tube has a mesh filter so would seem to be a
dedicated shower fitting. I need to know what they are so I can get
hold of a pair 1/2 longer (i.e. 3 inches)

I posted about this before, but did not make myself very clear, for
which I apologise.

Keith