An Ongoing Commitment to Improving Quality, reliability, and Safety Our mission at Superior Door & Gate Systems Limited is not to just satisfy our customers, but to astonish them! Superior Door & Gate Systems Limited has been the premier source of doors, gates, fences, security systems and dock equipment since 1977. Our expertise in the industry allows us to provide you with an integrated solution to all of your perimeter security needs, including design, fabrication, installation and service.