Major advantages of upgrading to this part/product: (1) 7075 alloy material, redesigned the motor mount can be adjustable , fits well with Original motor or bigger size motor such as "4985" (2) Works for below gear option:46 /27, 50/23, 50/24, 50/25, 52/21, 52/22, 52/23, 52/24, 54/19, 54/20, 54/21, 54/23