The hammer must pass a rigorous inspection to be certified for competition. It is the only implement in track and field that has moveable parts, and therefore must be strictly regulated. The following is an excerpt of some of the primary rules governing the hammer throw.
1. Implement must be certified for weight, length, diameter, handle and center of gravity.
a. Minimum weight 7.260kg senior men, 6.000kg junior men, 5.000kg youth men, 4kg women (senior, junior and youth)
b. Maximum length 121.5cm men, 119.5cm women
c. Minimum length 117.7cm men, 116cm women
d. Diameter of ball minimum 110mm men, 95mm women
e. Diameter of ball maximum 130mm men, 110mm women
f. Handle must form an isosceles triangle with the long sides equaling 110 mm, must be of rigid construction that will not stretch appreciably while being thrown
g. Wire must be unbroken, straight length of spring-steel wire not less than 3mm in diameter, which cannot stretch appreciably while being thrown
h. Center of gravity of the head of the hammer shall not be more than 6mm from the center of the sphere
2. Thrower must stay in the circle (7 feet in diameter) until implement lands.
3. The thrower must wait until the implement has landed before exiting the back half of circle under control.
4. Implement must land in sector (34.92 degrees).
5. Any throw that lands in the sector and is not a foot foul is a legal throw.
While different governing bodies have more specific rules about handle requirements and the acceptable tolerances of the materials used in hammer construction. These are the basic rules are fairly consistent across all leagues and levels of competition for hammer throwing.