This is a 13x7 Airplane Propeller that is a "tractor" (not a "pusher") Prop. FEATURES: Computer-optimized design gives these props a thinner profile and more "bite" with less noise. Lightweight molded nylon construction reduces rotating mass for higher output and longer life. Reinforcing carbon fibers help maintain true, constant pitch at any rpm. "C2" design (see COMMENTS). INCLUDES: One Carbon-Reinforced NYLON Propeller REQUIRES: ALL props require balancing. May need prop reamer. SPECS: Length: 13" Pitch: 7" Thickness at hub: 1/2" Hole diameter: 1/4" COMMENTS: The "C2" stands for the production run in which the prop was made.