PRSS 2017 Annual Report

58 The estimated fair value of short-term investments by contractual maturity as of December 31, 2017 is as follows (in thousands): Due within one year $ 5,666 Due after one year and through five years 341 Total short-term investments $ 6,007 3. Balance Sheet Items Inventory, net The following table shows the components of inventory, net (in thousands): December 31, 2017 2016 Raw materials $ 3,404 $ 3,422 Less: reserve for obsolescence (276) (303) Inventory, net $ 3,128 $ 3,119 Property and equipment, net The following table shows the components of property and equipment, (in thousands): December 31, 2017 2016 Land and building $ 3,675 $ 3,675 Computer equipment and office furniture 7,897 7,678 Computer software 1,925 1,795 Internal use software and website 14,270 11,207 Internal use software and website development in progress 204 849 Production equipment 14,435 13,685 Leasehold improvements 3,061 3,003 Total property and equipment 45,467 41,892 Less: accumulated depreciation and amortization (34,788) (30,956) Property and equipment, net $ 10,679 $ 10,936 Effective as of December 31, 2015, we completed the purchase of approximately 1.6 acres of land and an on-site building with approximately 25,000 square feet located in Louisville, Kentucky, to be used for our corporate offices. The total cash purchase price at the closing on December 31, 2015 was $1.8 million. We moved our corporate functions into the newly purchased building in May 2016. Depreciation and amortization expense was $4.7 million and $4.3 million for the years ended December 31, 2017 and 2016, respectively.