M: Dia 5.5 x 8 cm: KONG Extreme represents the most durable version of our original KONG toy. The ultra-strong, ultra-durable, black rubber compound is recommended for the most powerful chewers: Perfect for stuffing with KONG treats: Helps reduce boredom and separation anxiety for powerful chewers: Unpredictable bounce for games of fetch: Used worldwide by police, drug enforcement and military K-9 teams: Also used by Schutzhund and AKC competition trainers: Made in USA