Solid Brass Acorn Hex Cap Nuts Acorn nut is its common name and it is also called a crown hex nut, blind nut, cap nut or domed cap nut. It is a nut that has a domed top to cover the threads. This is to prevent contact with the external thread to protect the threads or protect other things the threads would rub against. A closed nut having a domelike cap over the back, protruding part of the engaged screw or bolt. Cap nuts, also referred to as acorn nuts are used to cover exposed bolt ends and add a finished appearance. These cap nuts are composed of a solid brass hex nut and top cap. General Product Information Size Drive Size Overall Height Internal Thread Depth 4-40 1/4″ Socket 1/4″ 3/32″ 6-32 5/16″ Socket 9/32″ 1/8″ 8-32 5/16″ Socket 9/32″ 1/8″ 10-24 3/8″ Socket 11/32″ 5/32″ 10-32 3/8″ Socket 11/32″ 5/32″ 12-24 3/8″ Socket 11/32″ 5/32″ 1/4-20 7/16″ Socket 3/8″ 5/32″ 5/16-18 9/16″ Socket 7/16″ 7/32″ 3/8-16 5/8″ Socket 1/2″ 1/4″ 3/8-24 5/8″ Socket 1/2″ 5/16″ 1/2-13 3/4″ Socket 9/16″ 5/16″ 5/8-11 1″ Socket 3/4″ 1/2″ 5/8-18 1″ Socket 3/4″ 1/2″ Shipping: All orders placed before 3:30 pm EST Will Ship Same Day Tracking is provided on ALL Orders Priority Mail Shipping service is offered at a discount of only $3.95 UPS Ground UPS Next Day Air is available, Please inquire for pricing Returns : ALL returns are accepted if returned within 60 days. Money Back or exchange guaranteed. NO Restocking Fees. For YOU, we constantly strive to find ways of improving our performance.