Eforstore 200pcs Glow in the Dark Stones for Walkway Fish Tanks Potting Aquarium Man-made Pebbles Luminous Stone Decorative Gravel Small Rubble Cobblestone for Garden Yard Glowing at Night Blue Material: Photoluminescent pigment + resin. Size of per stone: approx. 2.5*1.5cm. Line a walkway, edge a flower bed or fill a planter with these unique pebbles. After being exposed to daylight, these pebbles glow (green/blue) in the dark. Please attention: First use please exposed to daylight only 5-10 minutes these pebbles glow in the dark, Avoid exposed to daylight too long time,Otherwise it will doen't glow or glow faint. Glow lasts approximately two to three hours after soak up the sunshine 5-10minutes.