Years Ended December 31,
Years Ended December 31,
Years Ended December 31,
2019
2018
2017
Balance at beginning of period
$11,274
$17,067
$18,176
Remediation expense
2,602
1,182
307
Remediation payments
(2,455)
(6,967)
(1,416)
Other activity (1)
23
(8)
—
Balance at end of the period
$11,444
$11,274
$17,067
notes to consolidated financial statements -in thousands except for share and per share data .
note 10 — contingencies .
certain processes in the manufacture of our current and past products create by-products classified as hazardous waste .
we have been notified by the u .
s .
environmental protection agency state environmental agencies and in some cases groups of potentially responsible parties that we may be potentially liable for environmental contamination at several sites currently and formerly owned or operated by us .
two of those sites asheville north carolina and mountain view california are designated national priorities list sites under the u .
s .
environmental protection agency ’ s superfund program .
we accrue a liability for probable remediation activities claims and proceedings against us with respect to environmental matters if the amount can be reasonably estimated and provide disclosures including the nature of a loss whenever it is probable or reasonably possible that a potentially material loss may have occurred but cannot be estimated .
we record contingent loss accruals on an undiscounted basis .
a roll-forward of remediation reserves included in accrued expenses and other liabilities in the consolidated balance sheets is comprised of the following : .
-1 other activity includes currency translation adjustments not recorded through remediation expense .
unrelated to the environmental claims described above certain other legal claims are pending against us with respect to matters arising out of the ordinary conduct of our business .
we provide product warranties when we sell our products and accrue for estimated liabilities at the time of sale .
warranty estimates are forecasts based on the best available information and historical claims experience .
we accrue for specific warranty claims if we believe that the facts of a specific claim make it probable that a liability in excess of our historical experience has been incurred and provide disclosures for specific claims whenever it is reasonably possible that a material loss may be incurred which cannot be estimated .
we have an outstanding warranty claim for which we have not yet determined the root cause of a product performance issue .
testing is ongoing .
we are not able to quantify the potential impact on our operations if any because we have not yet determined the root cause .
we cannot provide assurance that the ultimate disposition of environmental legal and product warranty claims will not materially exceed the amount of our accrued losses and adversely impact our consolidated financial position results of operations or cash flows .
our accrued liabilities and disclosures will be adjusted accordingly if additional information becomes available in the future .

Question: Which years does the table provide information for A roll-forward of remediation reserves included in accrued expenses and other liabilities in the Consolidated Balance Sheets?
Answer: 2019 2018 2017