Generally speaking...
Face masks protect OTHERS.
N95 respirators protect YOU.

During a flu pandemic, face masks (like the ones surgeons and dentists wear) mainly help keep you from spreading germs when you cough or sneeze.  They protect other people from your germs.  If you're sick, wear a face mask to protect your family or other caregivers.  Use once; don't share.

Meanwhile, an N95 respirator helps block the viruses by filtering very small particles - including viruses - from the air you breathe.

Some of the product listings below are for a single package of face masks while other listings are for boxes or cases of larger quantities.  Face masks are intended for one-time use, then disposal (because flu viruses will be on the face mask).  So, buy an adequate supply.

Also consider buying extra to share with family, friends, or neighbors who may have lacked the foresight to buy a supply.