Who makes these Craftsman socket holders?

[m6z]

I'd like to order some socket nubs in a different size, but I'm not finding them on Lowe's or Craftsman's sites.

Thanks in advance.

 

[KnurledNut]

AFAICT, they are only selling the rails as a set of three. Which isnt cheap.
There is no option for individual nubs to date.
Typical SBD.