7/8" or 1" Square Center Hole1-3/4" Concavity11 Guage (3MM)All Blades are made in India or Brazil unless noted being made in China.We Can Get ANY Size Disc you Need so if you dont see it here, call us and we will find what you need.We Offer a Huge Freight Special on Large Orders of Harrow Disc! If you would like to Get a Special Freight Price Please Contact our Parts Department for Pricing!!!