The Seeland Heat waistcoat is made from a lined, lightweight fabric with stretch membranes in the sides. Inside, it has a heat-reflecting lining that not only prevents heat loss but also enhances the effect of the waistcoat’s heating membranes. The high collar is lined with soft fleece. In the parts of the upper body most vulnerable to cold – between the back and lumbar region – there are heating membranes sewn in. Using the associated smartphone app, these heating membranes can be set to the desired temperature between 30C and 52C. The membranes can also be set to 38C, 46C or 52C using the push button on the chest, so you are not dependent on your smartphone. Unlike older heating technologies on the market, the heating membranes in the Seeland Heat waistcoat are flexible enough to be folded up and packed away with the garment they are sewn into. The waistcoat can also be safely machine-washed. In the right-hand pocket of the waistcoat is a waterproof USB plug, so you can connect a power bank of your choice. With a power bank of 10,000mAh, the waistcoat can output its highest temperature of 52C for about 7 hours at an outdoor temperature of 0C. Once the waistcoat has reached the set temperature, the heat membranes automatically go into standby to save energy. They then turn back on automatically if the temperature falls 1-2 degrees below the level set for the waistcoat. The result is that the waistcoat is heat-regulating, because the heating membranes automatically turn off if you get hot from exertion and turn back on when you are sitting or standing still. The waistcoat has an inner pocket and two side pockets and is supplied with a drybag to pack it away in.