Plastic Combination Airbrick 220x72mm has been designed to provide high levels of ventilation into cavity walls and underfloor voids. The brick is stackable and can be joined together to create larger vent openings. It features a front mounted grill which consists of evenly spaced openings specifically sized to prohibit large insects gaining access but wide enough not to be blocked by debris, paint or water droplets. A mortar key around the edge ensures it can be securely fixed to the surrounding masonry.