Density and floor space according to cage typea.

aThe duplex cage consists of two separate cages; each has a floor area of 333.6 cm2 (51.6 in2). The shoebox cage has a floor area of 503.7 cm2 (78.1 in2).The housing density of Density group 1 is almost equal to that recommended by the Guide, which is 77.4 cm2 for mice between 15 and 25 g. Housing densities of groups 2, 3, and 4 are approximately 2.0-, 2.6-, and 3-fold greater. Numbers of mice were chosen to produce nearly equivalent densities between the two cage types. To complete replicate sets of cage densities, mice were obtained in groups of 31 for duplex cages and in groups of 46 for shoebox cages.