Fit all Annin cone-tapered aluminum and fiberglass poles. Cast of strong tenzaloy aluminum alloy and equipped with two machine-turned aluminum sheaves. Drilled and tapped for balls and eagles with 1/2\ dia. spindle. Styles 2S-R and 2S-HR are revolving trucks which rotate freely on 22 stainless steel ball bearings. Diameter: 5 1/2" Sheaves: 2 Bore: 1 5/8"""""