This is a heavy duty cutting edge to replace the standard mild steel wear bar / cutter edge used on John Deere snow plow blades. It's made of 1/4" x 2" AR/400 carbon steel for superior wear resistance. The extra steel in this blade helps stabilize the plow by reducing bounce. This is the toughest cutting blade available for the John Deere snow plow blades. Description Replaces factory part #M120139 for 48″ and #M75674 for 54″ blades 72″ model is for 54″ blades with 9″ John Deere extensions Made of super wear resistant AR 400 steel for maximum life Thicker cutting edge to help reduce bounce and prolong cutting edge life Includes stainless steel fasteners Laser cut holes for a perfect fit Will last 4-6 times longer than factory wear bar What is AR400 Steel? AR400 is a specialty steel designed at the chemical level for improved wear resistance for very specific applications. The steel is relatively expensive to produce, costing much more than simple mild steels such as A36 or 1018. However, the steel's special properties make it the only choice for applications such as blades in bulldozers. Because of the unique strengths of AR400, it is used in applications such as heavy machinery and steel plate applications. In addition to the abrasion resistance benefits, AR400 has increased impact resistance. This translates to digger blades and buckets on heavy machinery that can not only withstand impacts from stones and other debris, but the constant movement of dirt doesn't wear the steel down as quickly as other steels would.