The Dell R810,815,R550,R7610 rail kit is a replacement for the Dell rail kit that is provided with the R810, R815, R550 and R7610 servers. The R810/815 rail kit is compatible with 4Post and 2Post server racks. The Dell R810,815,R550,R7610 rail kit is a fixed rack mounting device. These rails will mount in a 4Post rack. They may also be center-mounted in a 2Post rack.