Here are some more of my growing collection. Back Row: Circle Triangle/Circle U (Line Material Co made by Universal Clay Products), T in a circle 2 in a circle (Thomas), PP INC/U.S.A. Drk Brown, Emily 1925-26 (back marked PP Inc.), Birnbach Radio Co. Cobalt Blue, PP Inc. Lighter Brown, Fleron Radio, No Name, Marked with a F, and last NN. Front Row: NN, IN-104/Isolantite, Sensory, No Name, Findlay 1926,NN, Fleron Radio, PP Inc.,Circle F, NN, another Birnbach Radio Co. showing the cobalt side.