Questions about Digitus DN-19 TRAY-2-1000-SW Pull-out shelf, 1U, 720mm depth

The following is included in the scope of delivery: - Installation set (screws, cage nuts, washers) - Handle Enclosed I link you to the data sheet of the product https://www.assmann.com/product-pdf/4016032180401?PL=de

According to my clarifications, the mounting depth is adjustable and the dimensions are: Max. adjustable depth of the mounting brackets of the shelf: 900 mm, adjustable mounting rails min.-max.: 665 - 770 mm