A slimmer version of the new Lenz Heat Sock 5.1 Toe Cap, the Slimfit gives smaller calves the nice smooth fit they’re looking for, whether you’re sliding these into your ski boots or pulling hiking boots on over them. One of the saving graces of living in the 21st century.. heated socks. And these socks have merino wool and a splash of silk for a smooth and supple sock with heating elements that go from your arch to right around all your tender toes, top and bottom, for maximum comfort in the cold. Compatible with the new Bluetooth compatible lithium pack rcB 1200 for smart phone control (with 14 hours of heat production), or the conventional lithium pack rcB 1800 with its button changed three settings and 20 hours of heat production, choose the pack that fits your needs (and level of technical prowess!). If you’re a “set it and forget it” user, the conventional pack will do you just fine. If you like to finesse your comfort, because you know you’ll be cold on the lift, but active on the slopes, you’ll love the ease of the Bluetooth battery. Either way, there’s nothing designed to generate more happiness than warm feet on a cold day. So get out there and be happy!