Clear non-ventilated polystyrene box with push-fit lid. Can be fitted with stainless steel gauzes by drilling hole and heating gauze to melt onto plastic. Also called Cadbury's box.
If you breed reptiles and require a cost affective method of housing reptile eggs for incubation then these are perfect. They double up also as housing for hatchling snakes but remember to provide ventilation holes around the tub.