Here are some of the small standoff insulators used for ham radio applications. Birnbach and Johnson were some of the biggest distributors of these. Left to Right: Johnson No 20, Next 3 are all Johnson No 22 just different shades of glaze, The smallest standoff Johnson No 24, Cone insulator marked I.C.A. 2307, Birnbach 478, Birnbach 966, Birnbach 958, Birnbach 998, No Name.