Financial instruments and related items, which potentially subject the Company to concentrations of credit risk, consist primarily of cash, cash equivalents and trade receivables. The Company places its cash and temporary cash investments with high credit quality institutions. At times, such investments may be in excess of the FDIC insurance limit.

The Company's revenues earned from sale of products and services for the three months ended March 31, 2020 included 24% and 54% (aggregate of 78%) from two customers of the Company's total revenues.

The Company’s revenues earned from sale of products and services for the three months ended March 31, 2019 included 13%, 32%, 30% and 14% (aggregate of 89%) from four customers of the Company’s total revenues. 

At March 31, 2020, there was no balance of the Company's total accounts receivable, and one customer accounted for 100% of the Company’s total accounts receivable with an amount of $750 at December 31, 2019.