6. Assets Held for Sale

Assets are classified as held for sale when, among other factors, they are identified and marketed for sale in their present condition, management is committed to their disposal, and the sale of the asset is probable within one year. For the three months ended June 30, 2021, the Company classified certain assets with a net book value of $5.2 million to assets held for sale. Management believes these assets are no longer necessary for the Company's future operating plans. Also, during the quarter ended June 30, 2021, the Company sold assets held for sale with a book value of $0.8 million. These assets were comprised of a battery breaker and related equipment.