Each pack contains 170 plastic pony beads. These beads are the same size as standard pony beads (4mm x 7mm with an inner diameter of about 2.5mm) and change colors when exposed to sunlight. If it's a bright, sunny day, the transition will start immediately any time you bring them outside and it will only take a few seconds to get to the fully changed colors.
Size: 6mm x 9mm with a 4mm hole.
Color: The beads are frosted white in the shade and turn purple, fuchsia, orange, and yellow in direct sunlight. If you're in moderate or indirect sunlight, like outdoors on a cloudy day or indoors in a room with a lot of windows, they will change color to a lesser extent; the less sunlight the beads are exposed to, the less vibrant and more pastel the colors will be.