heated insole , warm insole , winter insole , FIR Thermal InsoleHSP-75D Features:With FIR carbon ... working time Heated by powerful Li-on battery, the insole can heat for 3-6 hours each time after being ... inside it is very soft and foldable. Besides, the insole is easy to clean by just scrubbing with it ... insoles by cutting it along the white line on the insole. Benefit:1. Keep warm in winter time 2. ...