This is a Fingertip Prop or spinner back plate Balancer. INCLUDES: Two Blue anodized cones (aluminum) One Zinc coated steel shaft SPECS: Steel shaft: 5/32" w/32 threads per inch. Cones: Inner dia: 3/8" Total Length: 2-3/8" Outer Diameter: 15/32" Thickness: 7/8" js 07/06/94 ir/jl