Property and equipment consist of the following (in thousands):


	Estimated Useful
	Life (Years)		December 31, 2023			December 31, 2022
Land		—	$	875		$	875
Buildings	39-40			17,389			17,389
Building improvements	5-40			46,357			38,952
Machinery and equipment	3-15			60,410			58,542
Furniture, fixtures and office equipment	5-10			3,070			2,976
Computer equipment and software		3		8,658			8,246
Construction in progress		—		48,997			16,706
Total property and equipment				185,756			143,686
Less accumulated depreciation				(101,536	)		(98,560	)
Total property and equipment, net			$	84,220		$	45,126

Depreciation expense related to property and equipment for the years ended December 31, 2023, 2022 and 2021 was $4.5 million, $3.3 million and $2.0 million, respectively. During the years ended December 31, 2023 and 2022, the Company retired $2.1 million and $2.4 million, respectively of manufacturing equipment, computer hardware and software, computer equipment, lab equipment, and building improvements, as it was no longer in service. The net book value for the disposed assets during the years ended December 31, 2023 and 2022 was $0.6 million and de minimis, respectively.

In November 2021, the Company sold certain land, building and improvements located in Danbury, CT (the “Property”) to an affiliate of Creative Manufacturing Properties (the “Purchaser”) for a sales price of $102.3 million, subject to terms and conditions contained in a purchase and sale agreement. Effective with the closing of this transaction, the Company entered into a 20-year lease agreement with the Purchaser (the “Sale-Leaseback Transaction”). The sale of the Property and subsequent lease did not result in the transfer of control of the Property to the Purchaser; therefore, the Sale-Leaseback Transaction qualified as a failed sale leaseback transaction whereby the lease is accounted for as a

finance lease and the Property remains as a long-lived asset of the Company and is depreciated at its remaining useful life of 20 years or less. See Note 16 – Commitments and Contingencies.