This Airbrick has been designed to provide high levels of ventilation into cavity walls and underfloor voids. The 9" x 3" brick is stackable and can be joined together to create larger vent openings. The airbrick 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 of the airbrick ensures it can be securely fixed to the surrounding masonry.