What's in the box? 

• (1) Skywalker 23 Series Propeller Kit
• 1x Mount, 1x Washer, 1x Propeller Nut & 3x locking bolts

Bottomline

• An anti-loosen rotor design provides increased reliability: A copper pad and retainer spring are affixed to the core of the rotor shaft, and a sleeve is added to support the structure and prevent loosening.