0.500×0.500 Square on 0.750 Straight Centers 41% - 60%, Metal Perforation Patterns, OPEN AREA, PATTERN, SHAPE, Square, Straight 0.375×0.625 Oblong on 0.5625 Staggered Centers 0.500″ x 0.500″ Square on 0.750″ Straight Centers 45% Open Area