Wide Mouth Easy Sipper 53 mm by Nalgene
Ideally to your waterbottle 1 liter (32oz) with 5,3 cm opening (don’t fit the Nalgene OTF). Simply insert into the neck of the bottle. Solves the problem (the only disadvantage of the wide-necked bottles) that, when drinking, more comes from the bottle, than one can drink. Only infer for filling and cleaning. Polyethylene and in assorted colours.
Nalgene Sipper’ – for 53 mm black