The AF37SP is an A-Series panel board front trim — 37-1/2" x 20", surface-mounted, with a door-within-door configuration. NEMA 1 rated, so it's built for indoor general-purpose environments where falling dirt and light splash are the main concerns; no gasket seal against washdown or dust ingress. The surface-mount style means it bolts directly to a wall or structural steel, not flush-recessed into a finished wall.
Surface mount on a 37-1/2" x 20" footprint. The door-within-door design gives you a smaller access panel for daily operations (meter reads, breaker toggles) without swinging the full trim open — useful in tight corridors or where you want to limit dust entry into the main enclosure. NEMA 1 means no gasketed seal; if the environment carries cement dust or airborne grit, this trim needs a clean-room or filtered-air panel room to keep contaminants out of the bus and breaker compartments.