Something I found neat was the differences in the underside of these plastic insulators. L-R: CD 152/154- No Name, Flat pinhole, Flat skirt edges, Single groove on inner skirt. CD 154 No Name round head, Hard black plastic. Raised dot in pinhole, Flat outter skirt w/groove inside, Double groove on inner petticoat. CD 154 No Name Round head Shinny Black plastic. Curved in outter skirt w/single groove, Recessed raised dot in pinhole, Double groove on inner petticoat. Cd 154 types marked CTM and L-W Black plastic. rounded outter skirts Circle in top of pinhole, reinforcement ribs on inner petticoat, Extended groove up in inner skirt, Both have a copper embossing slug outline around embossing. Assuming they were both manufactured by the same type of mold. Last is the CD 154 types marked CEECO, CTC, & REN Black plastic, Flat pinhole, Rounded skirts, All three have the same size letters and a number below the embossing. Assuming again that these are all the same molds. Just for reference, the CD 155 type mexican insulator has a flat pinhole, Curved in outter skirt, flat inner petticoat and fits a standard U.S. 1" pin.