Exo Terra Turtle Pebbles are smooth river pebbles that have rounded over time in fast moving rivers. The smooth pebbles prevent injury to bottom dwelling or foraging turtles. The variations of colours and patterns create a natural looking riverbed. Exo Terra Small Turtle Pebbles (PT3830) is perfect for turtles with a shell diameter of 4”/10 cm or less. To prevent accidental ingestion in turtles with a shell diameter larger than 4”/10 cm, use Exo Terra Large Turtle Pebbles (PT3833). Easily clean & re-use Exo Terra Turtle Pebbles by soaking & disinfecting them in a large bucket of water for 15 minutes, rinsing until all of the visible particles are removed and the water runs clean. Small Natural River Pebbles (PT3830): Round pebbles (8-10 mm / 0.3”-0.4”), safe for all turtles up to 4” or 10 cm.