Other publications have suggested using pallet wood for small animal cages or fences. They are then kept in covered cages or boxes. Contaminated fomites such as clothing, food, cages, bedding, feeders, and water also spread the virus. Other accessories include lights, reflectors, mirrors, racks, trailers, bags, water bottles and cages, and bell. This is observed more frequently in birds reared in cages rather than on the floor. They also mandated enclosed roll cages. Inner nets, which wrap around the cages, hold the salmon. They are purpose bred and live their lives in cages undergoing experiments. These include cricket cages and wooden Japanese footwear called geta. Enrichment of laying hen cages ultimately results in better bone quality. The machine induces a voltage between two metal cages, inside a vacuum. Solid cages generally attenuate fields over a broader range of frequencies than mesh cages. Often, ions collide with the cages or wall. The arrangement of the cages (net pens) varies considerably. The dance floor featured several dance cages.