Guards, casts and braces must meet the following guidelines, EXCEPT:
a. Hard and unyielding items (guards, casts, braces, etc.) on the upper arm or shoulder must be padded
b. Knee and ankle braces which are unaltered from the manufacturer's original design
c. A guard, cast or brace made of a hard and unyielding substance may not be worn on the elbow, hand, finger/thumb, wrist or forearm.
d. All of the above
According to 3-5-2, you would think that c might be the answer as the rule reads "shall".