What sort of fitting is this?

[eveares]

What sort of fitting is shown in my photo below and is it maintenance free in the sense that it can be buried behind plaster? It certainly does not look like your typical soldered joint or compression fitting. Mine also freely rotates.

Fitting before radiator valve:
[GALLERY=media, 97211]Type of fitting? by eveares posted 29 Feb 2016 at 2:00 PM[/GALLERY]

 

[muggles]

It's a Tectite Sprint. Protect both it and the pipe by wrapping with tape prior to plastering