KONG Extreme Ball Dog Toy, Size Small (4 Pack) Pack of 4 KONG Extreme Dog Toy, Black Size Small 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