What does "Due to varying systems layouts HDMI port may or may not be available" mean?

I am looking at purchasing a refurbished Xbox 360. One of the sites I am browsing says

Due to varying systems layouts HDMI port may or may not be available

What does this mean exactly?

It means exactly what it says. Basically with a refurbished model, you aren't guaranteed that you will get a specific model - you might get one that is an older model without an HDMI port, or you might get a newer model that has them.

Basically, whoever you are buying this from is basically covering their proverbial butts, just in case you get one without an HDMI port and are like OMG THAT IS NOT AWESOME PLZ MONEY BACK NOW.