Dell Rails

ReadyRails - Quick snap in to the Sqares
Versa Rails - The Dell Versarail is designed to only work with 4Post Racks that have a rack mounting depth of 27 1/2″-29″. The Versa Rail Kit will also only work in a 4Post rack that has round, non-threaded holes.

Round to Square

http://www.provantage.com/supermicro-mcp-290-00060-0n~7SUP91F2.htm
http://www.amazon.com/MCP-290-00060-0N-Square-Round-Adapter-Retail/dp/B0037PF7PI
- I bought these to use in a sound isolating computer enclosure. The rack was built with threaded hole racks (audio guys building computer equipment .. go figure). I was trying to mount a dell server in the enclosure. Dell is making it increasingly difficult to use threaded hole racks with our equipment. I took a chance hoping this would save me from having to buy a pair of Versa rails. Unfortunately it does not work with Dell Rapid Rails. Vendor took almost a full week to ship it.