This is a quality thermostatic shower made by Meynell. It is quite old but has never been installed or used. I bought it to be installed in my previous house but we moved and it has sat in its box for years. This is not a power shower with pump but a simple gravity fed unit which should be simpler to install. I needed a shower head some time ago and used the one in the case but have replaced it with a new quality shower head.
If you know how to plumb in one of these, it could give you years fo good use. My house here already has showers and I no longer have any use for it.

Thermostatic shower (Malvern Wells WR14)