These Items Are Commonly Purchased Together:
This Item: 12 x 4.5 Quadcopter Prop Set (One Regular and One Pusher Prop)
KK Compatible Multi-Rotor Control Board (Blue Ver. 2.5 Firmware)
Price for all: $6
This is a set of two plastic Slow Flyer propellers,one normal and one pusher(reverse). You'll need 2x Slow Flyer propellers and 2x Slow Flyer Pusher propellers for a quadcopter. Each set comes with relevant accessories for mounting to different shaft sizes.