For the Max-Prop feathering propeller Designed for 3, 4, and 5 blade 70 mm and 99 mm max-props Suitable for shaft diameters from 1 1/4" to 1 1/2", and some 1 1/8" and 1 3/8" shafts Each anode has two 3 bolt patterns, making it compatible with any 70 mm or 99 mm Max-Prop Made in the USA - Mil-Spec