The Dewalt N842864 Reciprocating Saw Gearcase SA houses and supports the gears that transfer motor power to the saw's reciprocating mechanism. The gearcase helps maintain proper alignment of the internal components during tool operation. It is designed to replace a worn or damaged gearcase during compatible reciprocating saw maintenance or repair. Proper installation helps support smo... https://www.wholetoolbox.com/dewalt-n842864-reciprocating-saw-gearcase-sa/N842864.html