Features

The world's largest model propeller brand "APC Propeller"
It is a GF-reinforced nylon propeller designed and manufactured by USA Landing Product Company since 1989.
OK MODEL is an authorized distributor in Japan of Landing Products.

The size is expressed in diameter x pitch.
The unit is inches. (1 inch is about 25.4 mm)

The alphabet behind the size means the following.
W = Wide
N = Narrow
P = Reverse Pitch
PN = Pattern
E = For Electric Motor
SF = For Slow Fry
3B = 3 blades
4B = 4 blades