4. Inventories

Inventories are valued at the lower of cost (determined on a first in first out (“FIFO”) basis) or net realizable value and consisted of the following (in thousands):

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The non-current portion of inventories represents that portion of the inventories in excess of amounts expected to be used in the next twelve months. The non-current inventories are primarily comprised of repair parts for older generation products that are still in operation but are not technologically compatible with current configurations. The weighted average age of the non-current portion of inventories on hand as of March 31, 2022 is 1.2 years. The Company expects to use the non-current portion of the inventories on hand as of March 31, 2022 over the periods presented in the following table (in thousands):

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