I bought these two little nail knobs at an antique store today. Are they anything significant? I'm not into these little knobs, I mainly like big Pittsburg power porcelain. Here are the markings:

The small knob: SUPERIOR 5 1/2

Big one: PPIC [On top of] CNCO 4 It looks like a Porcelain Products embossing combined with a Pinco embossing. I'm thoroughly confused. Please help. Andrew