The Dell FX2 Quick Dry Slide Rack Rails is an alternative solution to the Dell rails that come with the FX2. The Dell FX2 Quick Dry Slide Rack Rails are designed to install in standard 19" square hole server racks. Compatible with round and threaded hole racks if hook plate is removed during install.The 122-5054 rail kit replaces the Dell rail kit. This rail kit is an excellent alternative to the original Dell rail kits if they have been lost, damaged or won't work with your rack. Dell rails do not allow this server to be mounted in a shallow rack, these rails are an option for shallow depth racks.