19 C.F.R. § 151.65
Duties on wool or hair subject to duty at a rate per clean kilogram may be estimated at the time of filing the entry summary on the basis of the clean yield shown on the entry summary if the Center director is satisfied that the revenue will be properly protected. Liquidated duties shall be based upon the Center director's final determination of clean yield. Estimated and liquidated duties on wool or hair tested for clean yield pursuant to the provisions of § 151.71 , and withdrawn for consumption without a change in condition which affects the duties and in a quantity less than an entire sampling unit shall be determined on the basis of an appropriate adjustment of the estimated percentage clean yield shown on the entry summary for the wool or hair included in each of the lots covered by the withdrawal. This adjustment shall be made by increasing or decreasing such estimated percentage clean yield of each lot by the difference between the percentage clean yield of the related sampling unit, as determined by the Center director, and the weighted average percentage clean yield for the sampling unit, as computed from the estimated percentages clean yield and net weights shown on the entry summary for the lots included in the sampling unit.
19 C.F.R. §151.65