6. Inventory

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Inventory as of September 30, 2023 and December 31, 2022 consisted of the following (in thousands):

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Inventory is primarily comprised of raw materials, work-in-process, and finished goods. The increase in inventory is primarily due to a combination of new product offerings and an increase in estimated future revenue. As of September 30, 2023 and December 31, 2022, the reserve for excess and obsolete inventory was $8.2 million and $5.4 million, respectively. Additionally, there was a lower of cost or market inventory adjustment of $20.7 million and $24.1 million for the three and nine months ended September 30, 2023, respectively. The lower of cost or market adjustment for the three and nine months ended September 30, 2023 was due to losses on new product offerings.