This is the Yukon Hardcore Locking Hub 35 Spline Driver. (Part number YHC73003) Kit includes both drivers. Yukon Hardcore Locking Hubs feature chromoly internals and all-steel construction for ultimate durability and strength. These hubs won't disengage under high torque applications and default to the locked position in use. Engagement comes from just a 1/3 turn of the all-steel, low-profile bezel, ensuring quick changes between two-wheel and four-wheel drive. Yukon Hardcore locking hubs are not only great looking, but feature a low-profile design to minimize impact with obstacles, as well as a proprietary coating on the locking gears for decreased friction and a long service life.