The KDF alloy column in the filter part of the straw measures 27mm wide (circumference) and 30mm high. (1.06" by 1.18").
I use it mainly to remove the iodine and or chlorine taste of my water and it does an excellent job at that. Since our tap water is treated with this type of purifier and hospitals and laboratories rely on this technology I think it's safe to assume it does what it's claimed to do. Other than that I like the fact that is virtually everlasting (up to 20.000 gal. cap. if point of entry influent water is free of debris, enter the millbank if it is not!) and a very lightweight and portable device.
Plus the fact if you are getting your water from places with industrial; mining or agricultural areas upstream were heavy metals and pesticides are especially a concern this Survival straw can be a big bonus as the regular chlorine (chlorox/MiOx,etc.) or iodine approach alone does nothing to rid your water of these contaminants.
I find it easier to have iodine or chlorox tabs plus this thing in my pockets or everyday kit than lugging a ceramic/carbon waterfilter around everywhere I go. A Millbanks bag/ iodine or chlorox / Survival Straw combo is extremely lightweight, virtually unbreakable and idiotproof. <img src="/images/graemlins/tongue.gif" alt="" />
Works for me !
Regards,
Pharaoh.