The Rambler Lowball is the ideal drinking companion. Easy to stack and store, the Lowball's double-wall vacuum insulation will keep your hot drinks hot, and your cold drinks cold longer than standard drinkware. Enjoy your evening whiskey by the fire, and refill with coffee the next morning. While the magnet adds an additional barrier of protection to keep drinks contained and prevent heat or cold from escaping. This magnet slider is not leakproof and will not prevent spills.