It looks like a piece of Obsidian from our nearby lava flows, but it&';s Gnawt-a-Rock(TM)! This durable throw toy is inspired by natural volcanic glass formed by rapidly cooling lava from Pacific Northwest volcanoes. Unlike Obsidian, the Gnawt-a-Rock is made with natural latex rubber, with a faceted, gum-massaging surface. Its irregular shape creates an erratic bounce, and it has a treat-dispensing design for interactive play and reward. Part of the Pacific Gnaw-west toy collection inspired by Ruffwear&';s home of Bend, Oregon, and its natural surroundings. Diameter: 4.5 (in), 11.5 (cm), Holds up to 2 cups of kibble. Please note: If any part of this toy becomes loose or detached, immediately take the toy away from the dog and discard the toy. ADDITIONAL FEATURES Erratic bounce for engaging fetch Faceted surface for gum-massaging Size suitable for large-mouthed dogs Made from natural rubber, a renewable, sustainable resource Made in Vietnam