All of our accordion shutters are very close in strength. One of the most reliable ways to tell the strength of an accordion shutter is: Maximum Span Also known as maximum height, can be found on the product approval form. Most accordion shutters have a maximum span of around 150 inches, with a -10/+10 difference being usual. Two of the accordion shutters that we manufacture have the highest span allowances in the industry; the Supernova Accordion Shutter, and the Impact Technology Accordion Shutter. Both shutters have a maximum span of 162 inches in height, although, we only will manufacture shutters up to 150 inches to make sure that we have maintain a Minimum Design Pressure of +40. Maximum Design Pressure When engineering and installing an accordion shutter, the shutter must meet minimum pressure required by the approving organization, typically +30 Design Pressure. Although, we design our accordion shutters to meet a minimum Design Pressure of +40 on large spans.