syringe filters!

could some one explain the syring filters as far as the filtering no.s and wich no filters out smaller particles high or lower no.s .45u .2um .22 .45 what does u and um stand 4 and wich one can u draw thru a syringe and then inject after use . Thanks alot.

Most people use .45 w/out any problems but .2 or .22 is a better way to go because it takes out smaller particles.

both should be used. .45 to take out the large stuff and then .2 to sterilize.

thanks 4 the insight guys!