QUALITY AIRFLOW – Save time, energy, and money with a Tamarack transfer grille. This user-friendly door vent eliminates air pressure imbalances in the home and increases your HVAC system’s efficiency. Most importantly, installing a Tamarack transfer grille is a simple way to improve the quality of the air you breathe. BALANCED AIR PRESSURE – Even with closed doors, the vent balances air pressure and prevents uneven room temperatures. The return air pathway decreases moisture in bathrooms and preserves energy throughout any building or home. The balance ensures that the inside temperature, humidity, air quality, and energy consumption levels stay right where you want them. COST-EFFICIENT – Great for Closed Appliance Zones, this vent extends the life of any HVAC system. Saving money on cooling and heating is a breeze with a Tamarack Return Air Pathway. Plus, this item is BPI Listed by the Better Performance Institute. LONG-LASTING – Made with durable, high-impact ABS plastic, this vent is covered by a lifetime manufacturer's warranty. While air flows freely between rooms, the internal baffle material prevents any increased transmission of light and sound through the vent/grille. EASY DOOR INSTALLATION – No need to install crossover or jump ducts with this convenient in-door vent. The kit includes a template for cutting exact unit measurements. This model is made for 1 ⅜ inch thick hollow core doors. The Tamarack Air Transfer Grill is an economical, easy-to-install, energy-efficient door transfer grill that eliminates air pressure imbalances and improves air quality. Made of ABS plastic. Includes 2 screws and template for cutting door.