Don't buy b/c the caps don't hold on to the can. I 30% of the cans I bought have this problem. I would hold off buying until they fix this problem. 2 stars b/c for the price.
These have gotten quite expensive in the past few years, but they do work well and are great to have around for cleaning dust out of many tight spaces. I use them several times a year, so a four-pack should last a couple of years or so. I'd recommend these to have around the house.