The 20"x24" table top exposure/burning unit is built of steel. Affordability is important in a start up screen shop, but don't let the price of this unit fool you. With this unit you are able to burn crisp images and bring a professional look to your screen printing shop. The built in automatic timer helps prevent over exposing and gives you the ability to multi-task with an automatic shut off. Average exposure time with this unit is 4 minutes.