Just replaced the blades and knives on the straw chopper on my 9610 john deere combine. Not sure of the metal. but it must be pretty good as they have chopped well over 50000 acres. The blades measure 8 1/2" x 1 3/4" x 3/16 thick, with a hole on one end that takes up about an inch. The knives are 7 1/2" x 1 3/4" x 1/16 thic, also with a hole on the end. I think they would be best used if they are forged. The price is right as all I want is postage.