What you are refering to is Flat Carpet Cable
It is/was NEC legal only installed under commercial carpet tiles (24"sq.)
Perelli was the mfg of the FCC, and Walker Duct the receptacle box and fittings.
Believe it or not, cleaning up the shop in June, I threw out the left-overs from the last installation. (Quite a while ago) You know how it is, you "save" the LO's in case you "need it". HA HA
Now I have to get the Code Book, and see if it's still listed.
I don't know if it's still available; Try "Walker Duct" on the web.