Maintaining a stable liquid temperature:
The bags are lined with high GSM English boiled wool, an excellent insulator. Even in damp conditions, boiled wool can absorb up to 30% of its weight in water without losing its insulating properties.

Protecting the Water Filters:
The hollow fiber membrane filters used in the bottles are vulnerable to freezing. Expanding ice can rupture the membranes, compromising filtration and allowing contaminants like bacteria and protozoa to pass through. The boiled wool lining stops freezing and protects against potential damage.

Hand-Loops:
We know the struggle of removing gloves in the cold! Each size bag has a large handle, allowing you to easily carry and fill bottles without removing the bag. The loops are spacious enough to use when wearing gloves. The handles are made from 12oz waxed Cotton canvas, and are double stitched at both ends for added strength.

Waxed Canvas Exterior:
The exterior of the bags are made from 12oz cotton, and have been waxed with the Martexin Original Wax blend which a virtually water-proof finish. Martexin Wax is made using a blend of non-hazardous food-grade waxes. The unique formula gives the fabric lifelong resistance to weathering and as it ages, it develops a well-worn patina.

Compatible with 32oz Bottles and Nesting Cups:
The nesting size is designed to accommodate standard size wide-mouth 32oz bottles. It's also large enough to accomodate a nesting cup. The drawstring helps cinch down any nested components, keeping them secure and preventing any rattling. Suitable for use with 32oz Nalgene & Pathfinder Bottles. The Front Pockets:
All bag sizes feature a spacious slide-in exterior pocket, designed to accommodate essential water gear such as a Millbank bag, water purification tablets, and electrolyte tablets. Our goal was to provide enough storage so all your water essentials can be kept together.

Belt Carrying Loops:
We've added two D-rings on the exterior of the bag, allowing it to be easily clipped to your belt, attached to the outside of your pack, or hung up inside your tent or around camp. Each bag also comes with two carabiner clips.

Disclaimers:
Disclaimer: Each bag is individually hand-cut and sewn, so slight variations in size and fit may occur. If you're not using the front pocket to store the Millbank bag, the fit around the bottles may be slightly looser.

What is a Millbank Bag?
A Millbank Bag is a water filtration device, designed to remove detritus including sand, mud, silt, and other suspended particulates from water. Even if there is no waterborne disease present, consuming turbid water can irritate and harm the digestive system.

Why Pair a Millbank Bag with a Water Filter?
While many water filters will filter out sediment, doing so significantly reduces their lifespan by forcing more debris through their filtration systems. By using a Millbank bag first, you reduce strain on your filter, extending its lifespan.