These rare, cobalt blue porcelain knobs are simply stunning! Paired with plain iron rosettes (R-01DE-R178-MB) , they work with everything from Greek Revival to rustic country. The shanks are powder coated to resist rust.Dimensions. Knobs: 2 3/8" diameter. Long shank: 5/8" diameter, drilled for a 20 TPI spindle. Spindle: 3 1/2" L x 5/16". Includes an Allen wrench and set screws for mounting knobs to spindle.