Up for bid is this C.T.D. Co. number 50 drill bit index for Fractional drill bits 1/2" thru 1/16". This having been made in Cleveland I would assume C.T.D stands for Cleveland Tool and Die Company but that's a guess. This index is in Excellent condition with no breaks or cracks and only some age patina to it's finish which I think is a plus. I will ship this item USPS Boxed Priority Mail for Free within the US. I also have a C.T.D Numbered drill bit index in similar ...condition up for auction in another listing. Please email me with any questions, thanks.