has anyone seen add-on fins for BB

oil-2-4-6-gas

1 time a long time ago i saw some alluminum fins in a c-clamp style a few feet in length of "Add-on" fins for baseboard --the product looked similar to a wire brush -in alluminum that could be wrapped around baseboard to extract some heat off of bare copper in between the fin-tube --i have a customer who had also seen this but had no idea where to find it or who made it ---anyone have a clue who actually made this stuff??