Bests & Worsts Reviews from Amazon

This "straw" only filters down to 3.0 microns. This will NOT filter out viruses. Minimum you should get is 1.0 micron rating or below as it will inhibit Cryptosporidium and Guardia (the cysts are larger than this in size). Even this is not really effective enough as most viruses cannot be inhibited by a filter with a micron rating of more than 0.01-0.03 microns. Do your homework before you buy any survival product!