Sleepypod's Limited Edition Critter Kit is designed to turn a Sleepypod Mini mobile bed for dogs and cats into a carrier for small animals such as ferrets, guinea pigs, hamsters, chinchillas and hedgehogs. The kit consists of a well-ventilated mesh hammock made of durable polyester and a litter tray made of heavy-duty acrylonitrile butadiene styrene (ABS), the company reports. The black accessories are designed to accommodate pets up to 3 lb. The hammock's hole is 4.75 in. x 8 in.