I bought this unit two years ago (it's supposed to be good for six?) and followed all directions, keeping it by my stove in case of fire. And a fire happened. Something is apparently wrong with my electric stove because I was only boiling water when flames started licking up the pot. I moved the pot, grabbed my fire extinguisher and set to work. Before I sprayed, it was on the green, full setting. It gave one poof of powder which lasted maybe a second, messed up my kitchen, and merely sneezed on the fire.
I eventually put out the fire by covering it with a lid, which slowed it a bit, and then put the rest out with baking soda. I'm so lucky that the fire didn't spread, but no thanks to this faulty extinguisher. It probably cost me a minute of fumbling because I kept trying to get it to work.
Don't take this as advice, but for myself I'm going to get a large bag of baking soda and keep it instead of the extinguisher. It won't be as good as a functioning extinguisher, but I'd rather go to something that I can trust and not waste time with faulty equipment.