Using the ASI 8155 Extension Sleeve is easy. First, make sure you have a rough opening that's 11 - 1/2 inches wide and 11 inches high in the wall. The wall thickness should be between 5 - 1/2 inches and 9 - 7/8 inches. If your wall is thinner, you don't need the sleeve. Once you've prepared the opening, install the sleeve with the ASI 8154 Specimen Pass Thru Cabinet. When it comes to maintenance, just wipe the sleeve with a soft, damp cloth to keep the smudge - resistant satin finish looking great. Avoid using abrasive cleaners as they might damage the surface. Also, check the heavy - duty piano hinge regularly to make sure it's working smoothly.