100 Sets Glow-in-the-Dark Size 20 KAM Snaps Halloween No-Sew Plastic Button Fasteners Cloth Diapers 100 complete sets = 200 caps, 100 sockets, 100 studs. All pieces glow in the dark. When exposed to light, the glow-in-the-dark snaps will "charge" and retain that light so that they will glow in darkness for a few minutes. It is unknown how long the glow property will last over time but line drying will help to preserve it longer. Size 20. 1/2" diameter cap. Requires KAM snap pliers or snap press to install (NOT included--see our other listings).