These insulators never underwent the final step in the molding process whereby the screwpeg and follower were inserted. Instead, some brave soul blew compressed air into the mold and created all manner of jagged bubble edges where the threads should have been. This trio spans a few decades, indicating the practice was not completely isolated. Shown are a script embossed Armstrong's DP1 at left, a Kerr era Armstrong No. 3 with no circle around the "A", and a Kerr DP1.