Review: £10 multimeters - Now includes the new RS-14!

[Nick]

... when you're dealing with picoamps, humidity and cleanliness are everything.

Absolutely - the soldering on these is "OK" at best, and there is no conformal coating, though you could add one easily enough.

If one was added, I'd like to think it wouldn't affect the calibration if done when the meter is fairly new - leave it (opened up) in the airing cupboard for a day or so, then spray the PCB...