Connects to bike’s 12V electrical system for fast warmth through chest, back, & complete arms. No lithium battery to charge. Hooks up to battery under seat with switch always accessible for quick easy use anytime. Used during cold weather rides, still looks like new. Excellent condition. Feels like warm electric blanket wrapped around you. New ones are $250, some bad reviews. This has always worked with no problem. Has hook ups in sleeves for heated gloves. I take size M or L, this liner fits under L jacket. No longer riding, sold bike. Many items to sell.