Check the listing for details. 8 x 3.8 SF Slow Flyer Propeller by APC APC08038SF. Condition: New. Listed at 2.45 USD. This is a 8x3.8 Slo-Flyer tractor (not a pusher) airplane propeller.This prop produces a lot of torque even at low speeds.Slo-Flyer props are Not designed for Glow engines. Key FeaturesComputer-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.Slo-Flyer propellers work well with Electric powered Park Flyer-type aircraft. IncludesOne carbon-reinforced nylon propellerOne set of small shaft locating ringsOne locating ring instruction sheet SpecsDiameter: 8Pitch: 3.8Hub Diameter: 0.50 in.Hub Thickness: 0.30 in.Shaft Diameter: 1/4 in.Engine Shaft Dia.Propeller Weight: 0.25 oz. RequiresALL props require balancing, this is VERY important