Keep your favorite hot beverages staying that way while you get the job done with these mug warming coasters. Made of iron with a woodgrain look and style, these 4.3″ round devices work via USB power to heat up drinks through heat conducive containers like paper cups, stainless steel, ceramic mugs and similar materials. Available in assorted colors. Add your school, sports team, organizational or company logo or message to customize. Orders of 100 units or more are eligible for sea shipping. Minimum order quantity or 25 pieces.