Regulation 6 Adjusting holes
(1)
No metric weight of less than 20 g and no imperial weight of less than 1 oz shall have an adjusting hole.
(2)
No other weight shall have more than one adjusting hole.
(3)
An adjusting hole shall be in the form of a cavity in a plane surface of the weight, and shall be
(a)
empty;
(b)
undercut and plugged with lead; or
(c)
closed by a plug or disc made of brass or steel.
(4)
Where an adjusting hole is closed with a plug or disc, the plug or disc shall, except in the case of a carat (metric) weight or an ounce troy weight, be secured by a lead pellet driven into an undercut recess or, if the cavity is threaded, into the thread so that it is not readily removable.
(5)
No plug, disc or lead shall protrude from the surface of the weight.