18. CONCENTRATIONS

During the second quarter of 2016, 28% of revenues were derived from two customers: Digi-Key Electronics at 18% in the Power and Electromechanical segment and National Grid at 10% in the Energy segment. Similarly, during the second quarter of 2015, 29% of revenues were derived from two customers: Digi-Key Electronics at 18% and National Grid at 11%. For the six months ended June 30, 2016, 30% of revenues were derived from two customers: Digi-Key Electronics at 19% and National Grid at 11%. For the six months ended June 30, 2015, 33% of revenues were derived from two customers: Digi-Key Electronics at 20%, and National Grid at 13%.

The Company’s major product lines during the first six months of 2016 and 2015 were power and electromechanical products and natural gas infrastructure and high-tech solutions.

At June 30, 2016, of the gross trade accounts receivable of $12.5 million, 16% was due from one customer in the Energy Segment: Socrate spa. At December 31, 2015, of the gross trade accounts receivable totaling $14.8 million, 11% was due from one customer: National Grid.

During the three and six months ended June 30, 2016, CUI had one supplier concentration of 9% and 8%, respectively, related to inventory product received. During the three and six months ended June 30, 2015, CUI had one supplier concentration of 9% related to inventory product received.

The Company had a revenue concentration in the United Kingdom for the three and six months ended June 30, 2016 of 21% and 22%, respectively. For the three and six months ended June 30, 2015, the Company had a revenue concentration in the United Kingdom of 21% and 27%, respectively.

The Company had trade accounts receivable concentrations in the United Kingdom and Italy of 27% and 18%, respectively, at June 30, 2016. The Company had trade accounts receivable concentration in the United Kingdom of 28% at December 31, 2015.