Pinheads

According to that source of all modern knowledge, Wikipedia, a pinhead can be:
a telemark skier
a pinball table fanatic
a juvenile cricket
a very dull or stupid person
a primary antagonist from the 'Hellraiser' series of horror films
a person with microcephaly - a neurodevelopmental disorder in which the circumference of the head is much smaller than usual

In this case, however, it is simply the head of a pin - lots of them ... in lots of different colours!