This is the Great Planes Standard (SAE) Precision Prop Reamer. FEATURES: Enlarges holes in propellers and spinner back plates-just turn the removable T-handle to cut perfectly centered 1/4" 5/16" and 3/8" holes Constructed of hardened carbon steel Stepped design increases accuracy Includes plastic storage case Can be used with a drill press for extra precision INCLUDES: One Great Planes Standard (SAE) Precision Prop Reamer with storage case SPECS: T-Handle Length: 2.75" (70mm) Reamer Length: 4" (102mm) Hole Sizes: 1/4" 5/16" 3/8" Standard (SAE) COMMENTS: Caution: Extremely sharp. Keep well oiled to avoid corrosion.