I recently bought a .010 Tecumseh piston (40045) that had that coating on it....at the machine shop the machinist stated it could withstand tighter tolerances....I don’t know, it sounded good....
I have LH 195(hs-50 sm bore) and that came with a coated piston. also note the design is different then my hssk50
numbers on the side cover.
when you look up the numbers i see the 40045 as the .010 piston rings.