Dont bother with the cheap powder ones. Theyre not worth a toss, and I found this out the hard way. It was the luck of god I had a bottle of drinking water with me or there would have been one less syncro on the road and a patch of melted tarmac in ballsbridge. After that I went and boughht a proper 2kg professional powder one with a pressure gauge and it was refillable. It was something like €40 but worth every cent for the peace of mind. Just remember to give it a good shake at every service, and mount it sideways instead of upright to prevent the powder caking up, rendering it useless. The ones you get in motor factors are bullshit. You need to go to a proper fire extingusher suppliers to get a good one.