Physical specifications for Synology RKS1317 Mount post width must be equal to or greater than 451mm Panel width must be equal to or greater than 480mm Rack mounting depth: 610mm~890mm Rack mounting holes must be square and at least 9.5mm x 9.5mm Synology Live Chat available – https://www.synology.com/en-global

A list of compatible models is listed here: https://www.synology.com/products/rail_kit.php?lang=enu
17-series: RS3617xs, RX1217(RP)
16-series: RS18016xs+, RS2416(RP)+, RX1216sas, RS816
15-series: RC18015xs+, RXD1215sas, RS815(RP)+, RS815, RX415
14-series: RS3614xs+, RS3614(RP)xs, RS2414(RP)+, RS814(RP)+, RS814, RX1214(RP)
13-series: RS10613xs+, RS3413xs+, RX1213sas
12-series: RS3412(RP)xs, RS2212(RP)+, RS812(RP)+, RS812
11-series: RS3411(RP)xs, RS2211(RP)+, RS411, RX1211(RP)
10-series: RS810(RP)+, RX410
9-series : RS409(RP)+, RS409, RX4