I know this.  Read the fine print.  I didn't do that.  The rest is geeky details having to do with rack-mountable servers.

I have a 12U rack.  Sort-of an end-table next to the couch.  I have two servers.  One of them is happily racked.  The other one is awkwardly sitting sideways across the top of the rack.

I jumped on eBay a week ago, looking to find the rails I need.  Server rails are very specific to make, one or two models and generation for a specific server.  Once a server is over a specific age, you can't buy them new, and eBay is the place where the used server stuff always shows up.

I found the rails I needed for the make and model I needed for a fair, but not ridiculous price (in either direction).  But ... I didn't read carefully enough.  The word "OUTER" was included in the description, and I saw that, but -- rails go on the outside of the server.... I didn't really think about what that meant.

Each rail set has four parts.  Front and back of the part that attaches to the rack.  A middle drift bar that extends half-way out of the rack-side rails.  Then there's the INNER bar that attaches directly to the server, and slides into the OUTER rail set.  There are cool counter stops built in so once the server is in place, it can't be pulled off of the set without some careful screw-driver use.  Ultimately, though, for each side, I got three of the four pieces I need.  Outer (2), Middle (1), but no Inner.

Is this the seller's fault?  No.  The words were there, I just didn't really internalize what they meant.  I am a bit miffed that I am not able to find JUST an inner rail set for less money.  This means that for ANOTHER $25 I'm now ordering another set, this time it has the words "INNER OUTER".  I figure if it doesn't include the middle rail, I got that in the set I already have.

I love and hate eBay.