If its anything like the home bargins one, it will brake after 3 uses lol Just fell to pieces inside. At least it managed to pump my wheel up enough for me to get off the motorway after a puncture. I've got a halfords only now that i got for £7 which is good for blowing up a tyre but the PSI meter is inacurrate by at least 2psi. All the portable ones are crap so use a petrol station one (some are free) but as a emergancy compressor it might be ok.
I went to get some air in tyres and water for windows the other day at BP and they wanted £1 for 4 minutes usage! Used to be 20p for air and free water.