10.         Balance Sheet Detail:

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Equipment and leasehold improvements consist of the following:

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During the three months ended September 30, 2024 and 2023, depreciation and amortization expense remained consistent at $0.1 million, respectively. During the nine months ended September 30, 2024 and 2023, the Company recorded depreciation and amortization expense of $0.4 million and $0.5 million, respectively. 

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In limited circumstances, the Company offers extended payment terms to customers for periods of 12 to 36 months. The related customer receivables are classified as accounts receivable long-term and discounted to their present value at prevailing market rates at the time of sale. In subsequent periods, the accounts receivable is increased to the amounts due and payable by the customers through the accretion of interest income on the unpaid accounts receivable due in future years. The amounts under these long-term accounts receivable due within one year are reclassified to the current portion of accounts receivable. Accounts receivable long term, net consists of the following:

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The undiscounted cash flows to be received by the Company relating to these accounts receivable long-term is expected to be $0.4 million during each of the 12-month periods ending September 30, 2025, 2026, and 2027.

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Accounts payable and accrued expenses consist of the following:

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