These nice water bottles are made of a very soft low-density PE (polyethelene) plastic, which can be recycled.
They are the standard size bicycle water bottle made to fit in all standard cages.
These bottles are special enough to be imported from Europe, made by Eurobottle. Throughout the years I've tried many styles of bottles, but always liked these the best because:
Wide mouth for mixing drinks and inserting ice cubes.
100% leak-proof top (it will blow the cap off violently if you try to carry carbonated beverages)
No funny plastic taste.
Easy to clean and doesn't easily grow mold, if you rinse them out.
Dishwasher safe.
Valve opening is large enough to gulp water.