The large opening on the wide mouth bottles easily accommodates ice cubes, fits most water purifiers and filters and makes hand-washing a breeze.
Nalgene says:
Original Polycarbonate Round Loop-Top bottle. Our most popular bottle. Our durable caps are made to mate perfectly with our bottles creating a leakproof system.
The attached loop-top never gets lost and screws on and off easily. Dishwasher safe (top rack please make sure the top does not touch the heating element or it will melt). BPA free.
The classic Nalgene bottle. Graduations in fluid ounces and milli-litres (ml).