My growing collection of porcelain Telephone/Radio Bridle and Ring Insulators. From left to right...Back row: Brunt, Knox, No Name, T in a circle (Thomas),T in a circle, T in a circle. Front Row: U.S.A.,NN with 4 circles, NN with 2 circles, NN Black, No Name, Marked with a small star, NN, NN bright white, NN, NN. Sometime in the future I hope to find some from New England Tel & Tel and Southern Mass Tel Co's. Bridle Ring Insulators were screwed into the outer wall to guide telephone wires down to the entry box which led into the house or building..