The Mobile Warming Bluetooth-enabled Primer Plus heated baselayer shirt is designed for the outdoor enthusiast to keep your core warm. Its moisture-wicking, warmth, and stretch features make it a versatile baselayer in the winter, or a standalone shirt during outdoor activities. The Primer Plus is made from a four-way stretch anti-microbial 88% polyester and 12% spandex blend that provides a comfortable next-to-skin feel. Flat-lock seams, moisture-wicking mesh liner, and side-stretch panels conform to your body and allow for maximum body movement. The Primer Plus heated baselayer has integrated, concealed heating panels powered by sturdy yet light-weight 7.4-volt Far-Infrared Heating System. There are three heating elements, one on the back and two on the chest. The heating system can provide temperatures ranging from 135°F on high to 90°F on low. On high, expect 2.5 hours of heat, and on low for up to 10 hours. The Primer Plus has two ways to adjust the temperature. First, the built-in touch control button. With a simple button push, you can select from four heat settings. Second, Bluetooth control is available with the MW ConnectTM app. Through the MW ConnectTM app, you can adjust individual heat levels to your liking. MW ConnectTM allows you to get real-time updates on battery levels and update your garments when new firmware becomes available. Includes the 7.4V (2200mAh) Lithium-Ion battery and a micro USB charging cable. You can expect up to 10 hours of heat per charge.