This is a 11x8 airplane propeller. It 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 11x8 Carbon-Reinforced NYLON Sport Propeller REQUIRES: ALL props require balancing, this is VERY important, use TOPQ5700. May need prop reamer, use GPMQ5005 (SAE) or GPMQ5007 (Metric) SPECS: Length: 11" Pitch: 8 Thickness at hub: 1/2" Hole diameter: 1/4" COMMENTS: The "C2" stands for the production run of this propeller.