You don’t mention which shower you have.
However your enquiry came from the Triton Rapide 2 page.
http://www.showerdoc.com/shower-http://www.showerdoc.com/shower-spares/triton/TRITO-PARENT-99-Triton-Rapide-R2spares/triton/TRITO-PARENT-99-Triton-Rapide-R2
And the cover for that is part 10 here is the link
http://www.showerdoc.com/shower-spares/triton/TRITO-P15920601-Triton-Cover-Assembly-RAPIDE-R2-COVER-----P15920601
If you have a different shower can you let me know which model it is
The cover assembly comes complete with the knobs.
Here is the link
http://www.showerdoc.com/shower-spares/triton/TRITO-P15810600-Cover-assembly-IVORY-3