Hi, I bought a new mixer shower. Was hoping to just swap the old bar for the new... never that easy though. The original pipes are only projecting past the tiles roughly 25mm. They are those z type fittings to adjust to 150mm centre. I reckon if I can extend these by 10mm I can get enough thread into the bar to avoid leaks. I was looking at these but unsure if they need a washer between it and the piece I want to extend from? I’ll also attach a pic of what I’m extending.