I was a volunteer fireman for about 20 years, and here is a little tip I learned along the way. The way the rigs bounce & vibrate going down the road, the powder inside them can become packed. If this happens, when you squeeze the lever either nothing but gas will come out, or not all of the powder will come out. So, before you squeeze the lever, if you'll hit the bottom of the extinguisher on the ground/pavement hard enough to loosen the powder, they should work like they are supposed to. It would be a good idea to learn how to use extinguisher because through the years I've been fo numerous scenes where someone tried to use one, did it improperly, and didn't put out the fire, when if they had known how to use it, could have put out the fire!