Fitting Shower Wall Elbow

[Retroelec]

Hello
I have got a Roper Rhodes shower elbow - SVACS08 and wondering the best way of fitting it.
There is a male thread on the back which I assume can screw onto a elbow wall plate but no fixings on the plate itself so what keeps it tight to the tiles?
If it is just the the tension between the plate and the elbow how can you make sure the elbow is tight and pointing the right way and wound far enough into the wall plate?
Pipework is on a dot and dab wall so no access behind.
Not tiled yet but just wondering if they are a nightmare

Thanks

 

[ShaunCorbs]

Any chance of a few pics as I don't know that shower ?

 

[Retroelec]

Its this one.
Not at home at the moment so cannot take a pic of the back but its just a solid male thread that fits in a 1/2" wall elbow plate.

 

[Retroelec]

No instructions with it either.

 

[ShaunCorbs]

Yes normally a 1/2 backplate elbow behind fixed to the wall

then you measured from inside the elbow (threads) and minus a few mm for it to tighten into to the finished tile (if you have to cut the brass tail)

But your correct no fixings just screwed into the backplate elbow