This is the ElectriFly by Great Planes 2¼" Transparent Blue Spinner. FEATURES: Great upgrade for Great Planes E-Performance series ARFs Lightweight aluminum backplate with stepped adapter hole for easier more accurate reaming Drilled for ¼" (6mm) shaft with drill guides for 5/16" (8mm) shaft One year limited warranty INCLUDES: Spinner, backplate and two phillips head screws Instructions inside header card REQUIRES: Installing on motor shaft SPECS: Length from Backplate to tip of Spinner: 2.2" (56.5mm) Diameter: 2¼" (57mm) Weight: .70oz (20g) COMMENTS: Also available in Transparent Red GPMQ4725, and Transparent Black GPMQ4724 jxs 4/13/07 ir/jxs