Lower part

Hello,

I can't be sure of what you have based on your description but your photo reminds me of a jamb liner from the side of the windows, which uses internal springs to support the weight of the window. If that is the case, unfortunately, that is not something that we can supply but a local millwork may be able to help if you have wood windows. 

If it is a bottom track for a sliding closet, take a look at our selection here depending on the length that you need. Just let us know if you have any other questions and thanks for posting!

Profile view of sliding mirror door bottom track