Warming trays or buffet warmers are necessary kitchen appliances for food warming, especially when many don't prefer microwaves for safety reasons. For hotels and restaurants, food warmers are of great use when the food is ready, guests are late, or events are pushed back. These scenarios do happen quite often, and it's always better to have several on hand in case of an emergency.
Today, there are numerous food warmers, and many of them use candles and chafing fuel; some have power cords, while some are designed to be preheated in an oven. For safety and convenience, not needing to search for power plugs, we always recommend the portable cordless electric buffet food warmers that can last for 2-3 hours.