Does anyone make taper/exposed core flats?

[FbassDave]

I wanna try some flatwounds on my Fbass - i love the feel of the Labella Super Steps I have on there already, and find the action to be supreb on anything else I put these strings on.
Does anyone know of a manufacturer that uses stepwound/taperwound/exposed core ends on their flatwound strings?

[Joe Smithberger]

LaBella, Smith and Sadowsky for sure taper their B strings, but I have never heard of a Super Step type set of flats.