50 Racer's Edge Prop Sanding Blocks. These are used not only to sharpen but also to clean up small nicks (which can develop into cracks) on the leading edge.  
 
This leading edge is important to durability and propeller performance, as the angle of finish directs the flow of water onto the face of the propeller. The geometry of how you sharpen the leading edge can change the lift and ultimately the performance of your go-fast boat.
 
These small sanding block squares are intended to be folded 4-ways to produce the crafty leading edge finish you see from some of the world's top prop shops.
 
Includes fifty (50) Racer's Edge Prop Sanding Blocks.