Whether you are talking about single doors, double doors or double egress doors, these get used a lot. You want a product that is built to last and up to the task. That is just what you can expect from the AO19-1, AO19-2 and AO19-3 series. What's more, these products are economical. They work with existing access control, locking and computer signal devices. The heavy duty construction reduces service calls and they are easy to maintain.