6. Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):

​

​

Depreciation and amortization expense related to property and equipment was $0.6 million and $0.3 million for the three months ended June 30, 2021 and 2020, and $1.1 million and $0.4 million for the six months ended June 30, 2021, and 2020,respectively.

Leased equipment and the related accumulated depreciation were as follows:

​

​

Depreciation related to leased units was $0.6 million and $0.3 million during the three months ended June 30, 2021 and 2020 , respectively. Depreciation expense related to leased units was $1.0 million and $0.4 million during the six months ended June 30, 2021 and 2020, respectively. Depreciable lives are generally 7 years, consistent with our planned and historical usage of the equipment subject to operating leases.

5.     Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):

​

Depreciation and amortization expense related to property and equipment was $1.1 million and $0.5 million for the years ended December 31, 2020 and 2019, respectively.

Leased equipment and the related accumulated depreciation were as follows:

​

​

Depreciation related to leased units was $0.9 million in 2020 and $0.3 million in 2019. Depreciable lives are generally 7 years, consistent with our planned and historical usage of the equipment subject to operating leases.