B&Q have a Monument brand or make 'Dry test kit' (£34.98). There are
no visible instructions, but appears to be a 4bar pressure gauge, with
a push fit(?) connection to 15mm tube(?) in the base plus a schrader
valve in the side.

Has anyone used one? If so, a quick how-to-use run through would be
appreciated + whether it does a good job + value for money.

Immediate queries on inspection were (1) what is the exact connection
type in the base? (2) how do you pump up the pressure - is a tyre pump
sufficient or do you need a 'proper' pump? (3) If a leak did show up,
how easy is it to pin point the failed joint?

If it is OK, then are any alternatives worth a look?

TIA