SmarTube cap for 37 mm Nalgene narrow mouth bottles and U.S. military and other canteens.
Here's what other sites are saying:
Description of SmarTube Cap 37mmThe SmarTube is a drinking system (hydration system), comprised of a drinking tube that fits any standard water bottle. Using SmarTube you eliminate the need to buy a hydration system with a water bladder. Instead you use a standard water bottle you can find anywhere and it's always clean. It's so clear.Features:SmarTube cap for 37 mm Nalgene narrow mouth bottles, U.S. military and other canteens
- US Outdoor Store