After a hard day bulldogging the sled, slide into the 509 Ignite Slipper Boot and enjoy warmth and comfort while your feet thaw out. With a high-traction lug sole, 200 grams of insulation with a micro fleece liner, and easy on-off opening, the biggest feature of these boots is the toasty power of Ignite technology. Low, medium, and high settings heat up quickly and stay warm thanks to built-in 2000 mAH li-ion batteries.