Each blade is 21" long, center hole is Bow-Tie, Outer 5/16", Center-To-Center 2-1/2", width 2.25", thickness .134", 1/4" offset, 15/16" lift Part#: BS703371 This Briggs and Stratton 21" Replacement Mulching Blade is a replacement part and ensures proper fit and performance to maintain the life of your equipment.