The Contractor is responsible for the delivery of each item quantity within allowable variations, if any. If the Contractor delivers and the Government receives quantities of any item in excess of the quantity called for (after considering any allowable variation in quantity), such excess quantities will be treated as being delivered for the convenience of the Contractor. The Government may retain such excess quantities up to $250 in value without compensating the Contractor therefor, and the Contractor waives all right, title, or interests therein. Quantities in excess of $250 will, at the option of the Government, either be returned at the Contractor's expense or retained and paid for by the Government at the contract unit price.