Adopts high quality ABS material, never rust, sturdy and durable for long term use. Quick and easy to install, save time and efforts. Widely used for freezer, air conditioner, cold storage and other refrigeration devices. Build-in temperature controller for better air ventilation, keeps the temperature within the window between +20℃ and 40℃ even if the indoor temperature(Freezer) is lower than -40℃. Effectively compensates for changes in pressure due to temperature dropping , avoids deformation of the insulating layer or impediment to open the door due to unbalanced pressure. Features: Adopts high quality ABS material, never rust, sturdy and durable for long term use. Quick and easy to install, save time and efforts. Widely used for freezer, air conditioner, cold storage and other refrigeration devices.  Build-in temperature controller for better air ventilation, keeps the temperature within the window between +20℃ and 40℃ even if the indoor temperature(Freezer) is lower than -40℃. Effectively compensates for changes in pressure due to temperature dropping , avoids deformation of the insulating layer or impediment to open the door due to unbalanced pressure.  Specification: Material: ABS Voltage of the applied machine: AC220V 36W(Heating) Size: Approx. 17.5* 17.5*10cm / 6.89* 6.89* 3.94 inch Package List: 1 * Pressure-balanced window 1 * English user manual 8 * Screws Features: Adopts high quality ABS material, never rust, sturdy and durable for long term use. Quick and easy to install, save time and efforts. Widely used for freezer, air conditioner, cold storage and other refrigeration devices.  Build-in temperature controller for better air ventilation, keeps the temperature within the window between +20℃ and 40℃ even if the indoor temperature(Freezer) is lower than -40℃. Effectively compensates for changes in pressure due to temperature dropping , avoids deformation of the insulating layer or impediment to open the door due to unbalanced pressure.  Specification: Material: ABS Voltage of the applied machine: AC220V 36W(Heating) Size: Approx. 17.5* 17.5*10cm / 6.89* 6.89* 3.94 inch Package List: 1 * Pressure-balanced window 1 * English user manual 8 * Screws