heated sleeveless vest for men integrated heating elements warm the lower back area and at kidney level Heating vest fits under any existing clothing system lithium packs sit in the inner vest pockets under the chest ribs can be combined with all Lenz lithium packs (optionally available) quick-drying, wind-repellent, breathable and abrasion-resistant material fleece insert in the collar small pack size and folds up small machine washable at 30 degrees