They can adapt to most any bladder or even a soda bottle.
I used the attachment for back flushing from a sink, to filter water from a sprite bottle, into my cup.
No moving parts to break.
I was told the word purifier is regulated, not used on most filters, is used on the Sawyer.
http://www.rei.com/product/781792I got a black one, Seems to cost more this year . note: the word purifier
More adaptable, last much longer, and less likely to fail.
Slower than a pump.
As with all filters, freezing enlarges the pores, fine print reads, "replace if frozen."