Threading mandrel for a threadless pin? Very old and just a cool go-with...stamped 1 1/4 on one side and 10 on another side. takes a threadless pin and turns it into a threaded pin. This cuts very well and a insulator will screw onto the pin after you make it..it cuts a straight side threads as threadless pins were straight anyway..... I'm not really sure if this is for the treadless pins as there is no manufacturer mark, just the size......you can let me know...I believe it is for a 1 1/4 x 10 threads per inch...size thread...........NOTE THE " V " SHAPED CUTTER......CUTS A ..... WWWW THREAD..I've seen the early pins from E.C.& M.Co. insulators and they had the same cut threads on their wood pins.......Rarer than any threadless and a great item for any early insulator collection...Just how many have you seen?....thanks