TR318 Glow in The Dark Garden Pebbles Stone for Walkway Yard and Decor DIY Decorative Gravel Stones in Blue(100PCS) Material: Photoluminescent pigment + resin .Size: about 20~30mm/Pcs. Eco- friendly: lighting these pebbles requires no electricity and no power.This is not only saving our money, but for saving the environment around us. These pebbles absorb sunlight during the day and light up at night.And they will glows for up to 2-3 hours after normal daylight exposure. Methods of decoration: Line a walkway, edge a flower bed or fill a planter with these pebble stones that will glow in the dark after being exposed to daylight.Ideal for waterscapes, landscape decoration, potted plants,edge a flower bed, lighting a pathway or driveway, gardens, crafts, aquariums, etc. Use multiple packs for larger areas.The pebbles are also safe for indoor use, but make sure to get enough sunlight for them to really glow once the lights go off!