All Foolproof sights (except TK models) use the Short Elevation Knob. The Long Elevation Knob is for use with Foolproof-TK target sights. The Elevation Gib Lock Knob fits both standard Foolproof and Foolproof-TK models
Big Book Catalog, Issue:65, Page:277
New Product Supplement, Issue:602, Page:015
SPECS: Aluminum, black, anodized. Steel screws. This may require fitting by grinding the tip of the threads to fit some sights.