This Wireless Battery Powered Foot Warmers with three adjustable heat settings,which is a perfect solution to your cold feet in winters,which keep your feetwarm and provide comfort.Features:Made of premium mutispandex material,breathable and comfortable.Three adjustable heat settings for your different demands. (40/104 42/107 45/113)Just shortly press once to switch different heating modes.USB charging from your usb charge adapter,computer,power bankandcar charger.(NOTICE: Input-DC5V 1A)Built-in wireless 3.7v 2800mAh rechargeable batteries for maximized operational comfort.The insoles can be easily cut into your size,provides comfortable fit.It is washable and reusable,and it is not suitable for machine washing.Ideal for working,backpacking,hiking,camping and fishing etc.Specification:EU Size: 38-40/41-45 (optional)EU38-40 Length: 24-25cm/9.4-9.8in (tailored)EU41-45 Length: 25.5-28cm/10.0-11.0in (tailored)Input: DC5V 1AMaterial: mutispandexHeating area: 10*5.5cm/3.9*2.2in (for forefoot)Temperatures40/104 42/107 45/113Power: 2* 3.7V 2800mAh rechargeable batteriesCharging time: Around 2.5hPackage size: 32*14*5cm/12.6*5.5*2inPackage weight: Approx. 390.4g/13.8ozPackage List:1* Pair of Insoles1* USB CableNOTE:1.Please choose DC5V 1A charger,power bank output port or others to charge.2.Do not charge the battery while working.3.This insoles temperature and heating time depend on room temperature and humidity.4.The insoles are with batteries,please take care to wash by hands.