P3 P8420 Rechargeable Hand Warmer (Black) Features: Warms to a safe temperature of 106 degree Super-slim, lightweight design Protective soft knit sleeve Can be recharged over 500 times Aluminum shell for thermal conductivity Specifications: Timer 2 - 3 hours Input: Power Supply 5v/1000mAh Max input Dimensions & Weight: Weight 1.6 oz.