UIM class F500 racing propeller. Fits 12:15 or 13:14 gear ratio with shaft diameter 15mm and shearpin 5mm.

About size(pitch and diameter) and cupping:

Pitch determines the max speed that this propeller can achieve.

Diameter varies blade area, therefore affects grip. Bigger diameter = more grip.

Cupping varies from 1-6, where 1 is very "slippery" and 6 has very good grip.

The recommended sizes are preselected for your convenience. If the propeller is to be used for UIM racing then preselected variant can be good average choice.