This is a 11x5 Pro Zinger Wood Propeller by J&Z Products. FEATURES: Fine crafted, wooden propeller for R/C aircraft Designed for the advanced competitive flier looking for the ultimate in performance and dependability Made of hard rock maple wood Clear coated natural wood finish Classic pointed tips INCLUDES: (1) Wood Prop SPECS: Center Hole Diameter: 1/4" Prop Diameter: 11" Prop Pitch: 5 REQUIRES: All propellers must be checked and balanced before using, can use TOPQ5700 Depending on the engine crankshaft size, the propeller may need to be reamed to a larger size using GPMQ5005 (SAE) or GPMQ5007 (Metric). MCW 8/31/03 ir/jxs