: Great! It keeps the NON-HARMFUL stuff out, but apparently it just lets all
: the HARMFUL stuff right through!?

: So, is this just a funny mistake on their labeling or did I buy the wrong
: kind of respirator?

The most harmful particles are the smallest ones, in the range of 1 micron in size. They get deep into your lungs and stay there. Most paper respirators filter out what are commmonly referred to as "nuisance particles", which are the larger ones that you can easily see. If you're going to do a lot of sanding, invest in a good respirator with replaceable dust cartridges. Most will also have organic vapor cartridges available for them so you can use one respirator for sanding, finishing, gluing, etc.