The Harkila Heat Long Johns are a pair of long underpants with built in heating membranes that can be set to exactly the temperature you desire. This makes them an excellent choice for a wide range of hunting and outdoor activities in the cold weather.

The Harkila Heat Long Johns are made from 80% nylon and 20% spandex, making them quick drying, stretchy and hardwearing. They have a modern cut, fitting relatively snugly to the body. In the parts of the lower body most vulnerable to cold - the lumbar region and just above the knees – there are heating membranes sewn in which, using a smartphone app, can be set to exactly the desired temperature between 32C and 43C. The membranes can also be set to 32C, 38C or 43C using the push button in the waistband, without using the app. Unlike older heating technologies, the heating membranes are flexible enough to be folded up and packed away with the garment they are sewn into. The long johns can also be safely machine washed. In the waistband is a long, fabric covered cord with a waterproof USB plug, for connecting a power bank of the desired capacity. The cord is long enough so you can keep the power bank out of the way in your trouser pocket, for example. With a power bank of 10,000mAh, the Harkila Heat Long Johns can output their highest temperature of 43C for about 7 hours at an outdoor temperature of 0C. To save energy, the heating membranes automatically go into standby once the garment has reached the set temperature. They then turn back on automatically if the temperature falls 1-2 degrees below the set level. The result is that the Harkila Heat Long Johns are heat regulating, because the heating function automatically turns off if you get hot from intense exertion and turns back on when you are sitting or standing still. The long johns are supplied with a drybag to pack them away in.

The Harkila HEAT User Guide can be downloaded here.

Main Fabric: 80% Nylon/20% Spandex, Single Jersey

Features:

• Soft elastic webbing at waist for comfort fit
• 3 heat panels: Lower back & knees
• Flap at waist with power button for easy access
• Full stretch