HEAT SOCKS SET XLP ONE - CLASSIC Powered by high capacity, lithium-ion Battery Packs, Hotronic's Heat Socks XLP ONE offer three (3) base level settings for comfort and warmth maintenance while Boost Setting 4 offers an extra blast of heat when needed. The Heat Socks Set XLP ONE - Classic Include: Battery Packs XLP ONE (2 each) Recharger XLP (1 each) Heat Socks XLP PFI 50 - Classic (1 pair) Heat Sock Product Features: Includes 2 Lithium-Ion Batteries US and European Charger 70% Nylon/20% Spandex/10% Marino Wool Machine Wash/Air Dry Fantastic Wicking Ability Consistent Heating Power Perfect for Diabetics or People with Reynauds Syndrome Heat Sock Product Specification: BATTERY PACK XLP ONE: Weight: 76 grams / 2.68 ounces Height: 25 mm Width: 70 mm Depth: 35 mm Cell Count / Type / Capacity / Energy: 1 cell / Li-Ion / 2900mAh (nominal) / 10.4 Wh (nominal) Battery Pack Voltage: 3.6V (nominal) Temperature Range when Charging: +10 to +30 °C / +50 to +86 °F Operating Temperature: -20 to +30 °C / -4 to +86 °F Ideal Storage Temperature: -20 to +20 °C / -4 to +68 °F Charging Time: Approximately 5 - 6 h RECHARGER XLP: Voltage Input Range: 100V to 240V AC Voltage Output Range / Current: 5V DC / 3.1A Operating Temperature / Humidity: +10 to +30 °C / +50 to +86 °F +20% to +85% relative humidity (no condensation) Base Unit Dimensions (withOUT Plug Adapter): 54 mm x 54 mm x 27 mm Power Cord(s) Length (Base Unit to Plug End): 156 cm Weight (withOUT Plug Adapter): 5.1 ounces Weight (with Plug Adapter 120V): 5.3 ounces Weight (with Plug Adapter 240V): 5.6 ounces HEAT SOCKS XLP: Material composition: 74% Nylon 20% Elasthan 6% Merino Wool Possible Sizes: S, M, L and XL Care: Machine washable up to 30 °C (86 °F) / Air dry Hotronic Keeps Feet Warm: HOW FEET BECOME COLD: When colder outside temperatures are detected, the nervous system restricts blood flow to the extremities to maintain the body's core temperatures. The toes (and other extremities) q