I've had one for a few years and it works for me though haven't tried on full size African mozzies. I get a bad reaction from midge bites and 2 or 3 clicks as soon as possible and then again when it swells, usually 24 hours later. It stops me wanting to itch and consequently reduces the swelling.
Another advantage is that because I don't scratch there is no broken skin to get secondary infections.
Probably won't work for everyone but it works for me
"Never have a stupid argument with an idiot - he gets a lot more practice than you"
there I go again
not too hard really