These blades are more than 40 years old. My brother-in-law said that they were at the small machine shop he worked at and now owns. He gave them to me because he knew I had a scroll saw. They were made for a hand held coping saw, about 6 3/4" long. I cut them down to 5" with a wire cutter, flatten the ends with a ball peen hammer and use them in my saw. They seem to be the ideal spiral for a scroll saw. I can cut oak plywood all day and they seem to never get dull. They leave about a 1/16" kerf, I just wish I had other sizes. The company apparently is no lnger in business, I can't find out anything about them. I have tried the twisted spiral blades and do not like them. The compony is: Tyler Manufacturing Co, Inc. 516 5th Ave. New York 36, N.Y. and 1005 W, Arbor Vitea, Inglewood, CA. The patent # is 2.514.609