The proposals for such work and the contracts made with the parties successful in the competition, reserve the right to the Postmaster General to change the values, designs, etc., from time to time as he may judge expedient, and specify nothing as to these particulars, while they are very specific as to the quality of the work, and the precautions to be observed in the manufacture, to prevent pecuniary loss to the Department. A government official inspects the work in order that it may conform in quality to the contract, and the records are kept of the number of stamps of each value made and turned over to the Department, without further specifications.