Macerator

[boater sam]

Yes, tank connector without the back nut, 22mm X 3/4" BSP male. They used to be plastic ones too but with the rationalisation of stocks these days lots of fittings are less easy to find unless you want a full box of them. Just a bit tricky to cut the thread with a tap and to thread it in with it being on a curve but a very tidy job.