Section 13(3)(b) in The Rajasthan Weights and Measures (Enforcement) Rules, 1959
(b)no weighing or measuring instrument manufactured after the coming into force of these rules other than Class A beam scales shall be stamped unless provided by the manufacturer with a plug or stud of soft metal on which to place the Inspector's stamp, such plug or stud being made irremovable by undercutting or in some other suitable manner.