QNAP Rail Kits assist in the installation of rackmount QNAP NAS. The sliding rails make it easier to slide QNAP NAS in and out for easy maintenance and management. QNAP NAS rackmount models comply with ANSI/EIA-RS-310-D rack mounting standards. Before purchasing server racks, please make sure the server racks conform to the matching specifications. 1. Rack size A. Mounting post width_ ≥ 17.8" / 451 mm B. Panel width_ ≥ 19.1" / 485 mm C. Mounting post depth_ 18" ~ 32" / 443 ~ 815 mm D. The distance between two rack posts (center-to-center measurement of the rack's square holes) is 18.3" / 465 mm The rack kits are only compatible with 9.5 mm x 9.5 mm square-hole server racks.