Note 5.         Patents

Patents represent legal fees and filing costs that are capitalized and amortized over their estimated useful lives of 17 to 20 years or their remaining legal lives, whichever is shorter, after they are placed in service. For the three months and six months ended June 30, 2016 and 2015, we capitalized approximately $0.1 million and $0.1 million, respectively, for patent filing costs. The total investment in patents was approximately $1.0 million as of June 30, 2016 and December 31, 2015.

No amortization expense of patents was recorded for the three months and six months ended June 30, 2016 and 2015. These patents were not placed in service as of June 30, 2016 and December 31, 2015, or in prior years.