ProStar displays are large video screens consisting of high-density LED arrays. Developed by Daktronics , Brookings, S.D., they incorporate filters and EMI vents as part of their forced-air cooling — important because of the heat and humidity of ballparks in the summer time.
The signs originally used EMI shields consisting of honeycomb or perforated metal panels that were separate from air filters and permanently mounted. The shielding is necessary because air inlets and exhaust vents tend to be large and prone to act as EM radiators.
The signs now use combo EMI shields and dust filters from Universal Air Filter Co., Sauget, Ill. Dual EMI air filters are comprised of one compact, removable assembly that integrates the honeycomb and/or stainless-steel-mesh EMI shield into a single unit. Aluminum-framed Quadrafoam air filters have a foam-gasket seal around the perimeter of the frame and install on the intake side of the display enclosure. The filters' Quadrafoam media is an open-cell polyurethane foam treated with a thin coating of flame retardant. The coated foam also contains an antimicrobial additive with a fungus-growth rating of zero.
The same dust/EMI filters also go into the Galaxy line of monochrome and full-color displays used for on-premise advertising, typically in front of retail businesses.
Universal Air Filter Co., uaf.com