How it works
How Active Heat™ Technology Works
Every other answer to a frozen hydration tube slows heat loss. Active Heat™ replaces the heat instead. That difference is the whole product, and it is worth understanding before you buy.
The problem, precisely
Your reservoir holds a large volume of water with a lot of thermal mass, insulated by your pack and warmed by your back. The tube holds a thin column about 7.41 mm across, hanging in open air, often in wind.
That surface-area-to-volume ratio is why the tube always freezes first, and why the bite valve, the most exposed point, plugs before anything else.
Why insulation cannot fix it
Insulation slows the rate at which heat moves. It does not create heat, and it does not choose a direction. The water in your tube is already at ambient temperature, so a neoprene sleeve is insulating something cold from something cold.
It buys time. On a long, cold, low-activity day it runs out.
What Active Heat™ does
It warms the tube itself, continuously, through to the bite valve, so the water inside never reaches freezing. It runs from any 5V USB power bank at 1 to 3A, down to −1°F (−18.3°C).
It heats the tube, not the water. Your drink stays cold.
Adding heat versus preserving it
| Approach | What it does | Where it stops working |
|---|---|---|
| Warm fill | Starts the water above ambient | Runs out by mid-day |
| Neoprene sleeve | Slows convective loss | Water still reaches ambient |
| Blowing back after each sip | Empties the tube | One forgotten sip ends it |
| Tube inside your jacket | Borrows your body heat | Stops when you vent |
| Active Heat™ | Adds heat continuously | −1°F / −18.3°C |
Common questions
What is the Ever Flex System™?
Our name for keeping the assembly pliable below freezing. A tube that stiffens in the cold catches on your jacket and shoulder strap, which is a nuisance on a fast descent and a real problem at a transition with cold hands.
Does it get hot enough to be uncomfortable?
No. It warms the tube enough to stop water freezing inside it, not enough to heat the water. If the day warms above freezing you unplug the battery and it behaves like any other tube.
How do I know it is on?
There is an LED power indicator on the cable.
