I bought these pendants to replace ones that I installed several years ago - the monorail track was already in place, so all I had to do was buy new pendants. There were a couple of different styles of this particular pendant so I was not totally sure which ones to buy. A quick call to customer service was very helpful. They arrived carefully packaged complete with clear directions on installation. I could not be happier. I will be making all of my lighting purchases on this site from now on.