Anti bacterial/germs & thicker than most. Unlike other brands, do not need cleansing rituals to get rid of tastes and odours. I recommend all 4 of the sub £5 items.
About half-price the usual & unlikely to be matched in the future.
No need to crumple as below, folds flat:http://uk.youtube.com/watch?v=J244fgFRWsI
If you're not into backpacking, use for Colas, wines, spirits etc. to keep fresh sans-air.