I recently bought a "Tube O' Hay" with timothy hay. Basically, it's a tube with hay inside. The tube is made of cardboard. My pigs LOVE it!!!! It's great for them to play with getting the hay and once it's all out, it makes a GREAT tunnel!!!! I got it at Pets Mart for like $7. Also, the tunnel is big enough for just about any guinea pig to EASILY get through it. lol