LESYPET Fish Tank Glow Stone for Fish Tank Accessories Turtle Tank Accessories Decorations,Aquarium Pebbles,Fantastic Garden or Yard Mixed Color Material: Resin. Average diameter: 2-3cm/1 inch. Weight: 4g. Random color,50g equal to 15Pcs The light could glow in the dark for more than 6-10 hours after absorbing the sunlight for 10 ~ 20min. Fish tank glow pebbles stones glow in the dark perfect for tank aquarium decorations.Water, acid and alkali resistant, antioxidant Designed for use in Fish Tanks, Pools & Ponds. Can also be used for Gardens and Home Plant pots Lesypet Delivery: FBA (Fulfillment By Amazon) can be delivered in 1-2 days. Meanwhile, FBA can provide 30 Days Money Back Guarantee,easy to return. FBM (Fulfillment By Merchant) will take 7-14 working days, not as Amazon shows: 14-28 working days.