rail kit offers the following choices synology rks1317 rail kit sliding synology rkm114 rail kit mounted applied models synology rks1317 17 series rs3617xs rx1217rp 16 series rs18016xs rs2416rp rx1216sas rs816 15 series rc18015xs rxd1215sas rs815rp rs815 rx415 14 series rs3614xs rs3614rpxs rs2414rp rs814rp rs814 rx1214rp 13 series rs10613xs rs3413xs rx1213sas 12 series rs3412rpxs rs2212rp rs81