Aside from investments held in the Company’s retirement benefit plans, financial instruments that could potentially subject the Company to concentration of credit risk consist primarily of cash, cash equivalents, and trade receivables. The Company’s cash and cash equivalents are held and managed by recognized financial institutions and are subject to the Company’s investment policy. The investment policy outlines minimum acceptable credit ratings for each type of investment and limits the amount of credit exposure to any one security issue. The Company does not believe significant concentration of credit risk exists with respect to these investments. * Less than 10%. ________ The Company uses a significant quantity of raw materials that are highly dependent on market fluctuations and government regulations. Further, as a U.S. government contractor, the Company is often required to procure materials from suppliers capable of meeting rigorous customer and government specifications. As market conditions change for these companies, they often discontinue materials with low sales volumes or profit margins. The Company is often forced to either qualify new materials or pay higher prices to maintain the supply. To date the Company has been successful in establishing replacement materials and securing customer funding to address specific qualification needs of the programs. Prolonged disruptions in the supply of any of the Company’s key raw materials, difficulty qualifying new sources of supply, implementing use of replacement materials or new sources of supply, and/or a continuing volatility in the prices of raw materials could have a material adverse effect on the Company’s operating results, financial condition, and/or cash flows. As of December 31, 2020, 8% of the Company’s employees were covered by collective bargaining agreements. Warren G. Lichtenstein, the Executive Chairman of the Company is also the Executive Chairman of Steel Partners Holdings L.P. ("Steel Holdings") and the Chief Executive Officer of Steel Partners Ltd. ("SPL"). The Company received services of $0.1 million, $1.1 million, and $0.6 million in 2020, 2019, and 2018, respectively, from Steel Holdings and SPL, primarily included administrative services and the use of an aircraft for business travel. As of December 31, 2020 and 2019, the Company had liabilities due to such entities of $0.1 million and $0.1 million, respectively. Major Customers Credit Risk Dependence on Single Source and Other Third Party Suppliers Workforce w. Related Parties * Less than 10%. ________ 52 Year Ended December 31, 2020 2019 2018 RS-25 program 18  % 17  % 14  % Standard Missile program 13  13  13  THAAD program 11  10  11  PAC-3 program 10  10  8  Year Ended December 31, 2020 2019 2018 Lockheed Martin 34  % 33  % 30  % NASA 21  21  18  Raytheon Technologies Corporation ("Raytheon") 17  17  19  ULA * 10  17  As of December 31, 2020 2019 Lockheed Martin 21  % 26  % Raytheon 20  21  The Boeing Company 16  18  NASA * 14  The following table summarizes customers that represented more than 10% of accounts receivable, including unbilled receivables which are a component of contract assets:  The following table summarizes the customers that represented more than 10% of net sales, each of which involves sales of several product lines and programs: 