G.

PATENTS

During the three months ended December 31, 2021, the Company recorded approximately $31,000 in patent impairment charges. No patent impairment charges were recorded during the three months ended December 2020. During the three months ended December 31, 2021 and 2020, amortization of patent costs totaled approximately $14,000 and $13,000, respectively. Approximate estimated future amortization expense is as follows: