The requirements of this standard are such that most helmets will perform
optimally only when tested within a range of head circumferences.
Outside this range, helmets may still provide a measure of
protection but they may not meet requirements for certification.
The manufacturer must specify this entire range when helmets are
submitted for certification. Later, when helmets are distributed
for sale, every helmet shall include a permanent label indicating
the range of head circumferences for which it is intended.