Air-A-Lator 230380 3" The “Mason’s Choice” Flexible 3-Piece Kit. The Air-A-Lator® and the “Mason’s Choice” are the number one outside air intake regulators for masonry fireplaces. The fire will burn warmer, cleaner and more safe because regulated outside air is used for combustion. The homeowner can control both the volume of air and direction of air with these unique products.