To measure for an Irvine retractable shower door, measure the width of your shower opening at three points—top, middle, and bottom—and use the smallest measurement to ensure the door fits properly. Then, measure the height from the base to the top of the opening. Check that your shower walls are level and plumb using a level tool for accurate installation. The Irvine retractable shower door comes with its own mounting hardware and is designed to install independently, so it does not utilize the existing frame from OEM sliding glass doors. This ensures a proper fit and reliable operation when replacing your current shower door.