Arnold/Murray MRR-42A-CS 21-Inch Lawn Mower Replacement Blade - 2 Pack 92418 This blade replaces OE #92418. Fits 42" Murray lawn tractors (Contains 2 blades). 27/32" round center hole This is a duplicate of the original equipment blade that came on your mower/tractor from the factory. Arnold quality replacement blades fit exactly the mower/tractor they are manufactured for. Check the original equipment number to locate the correct replacement duplicate blade.