There are two types of aluminum alloy sliding doors: the 70 series and the 90 series. The 70 series can be used for aluminum alloy sliding doors inside residential buildings. The series number represents the thickness and structural dimensions of the door frame in millimeters. There are four types of aluminum alloy sliding windows: 55 series, 60 series, 70 series, and 90 series. The selection of the series should be determined based on the size of the window opening and the local wind pressure value. Aluminum alloy sliding windows used for enclosed balconies should not be less than 70 series.