Prevue pet products nature's hideaway medium grass ball 1094 is a hand-woven grass activity center for your small animal. the sweet fragrance of 100-percent all natural grass materials comes through in this fun playtime accessory while satisfying your pet's natural instinct to burrow, explore and nest. our medium grass ball is woven of primarily black grass, measuring approximately 7 1/2-inch in diameter, ideal for a hamster or guinea pig.