Check the listing for details. MS21042-L4 Reduced Hex Head Aircraft Lock Nuts (50). Condition: New. Listed at 17.95 USD. These are also referred to as light weight ”Jet Nuts”. 50 each new surplus MS21042-L4 Self Locking, Reduced Hexagon Head, Reduced Height, Ring Base, Steel Nuts with ¼-28 threads. The “L” designates that they are also “Lubricated”. These nuts are generally used in the aerospace industry. Many racers also like them because they are light. These nuts were purchased in a large aerospace industry surplus lot and there are no certs or traceability. Even though it is in new surplus condition, buyer is responsible to make sure that this part will work for their application as there is no warranty or guarantee expressed or implied. Please Note: Shipping charges are not refundable. Items are subject to a 20% re-stocking fee, on a case to case basis. If you purchase more then one item please wait for an invoice with a combined reduced shipping rate. Thank You