A pair of female mice in an Optimice cage,

Optimice housing units used in laboratory setting and in TAFE/educational facilities with animal courses. Mice may sometimes be provided a toilet roll as "enrichment," otherwise they are provided only food, water, litter, and a small amount of bedding material. Each cage is used to house up to 6 mice at a time, and kept in a large rack that can contain dozens of cages.

Mice are "ear notched" for identification purposes (holes are punched in their ears in areas that correlate to a number system). This is done without any pain relief, despite less invasive alternatives such as dye marking and fur trimming being well known and similarly effective.