17-5/8" diameter, .157" thick, 13 wave coulter. Has a 4" Center hole and a 4 bolt holes on a 5 1/4" bolt circle.Commonly used in the following applications:Ausherman no-till coulter attachments.Case-IH 5400 drills.Great Plains drills.John Deere 1570 coulter cart.Salford vertical tillage 570RTS, I-1100.Yetter no-till coulter attachments.