Using multiple Rad Disk™, it is possible to conduct sequential irradiations on groups of up to 20 mice (without dividers) without the need of autoclaving cages between each use, because the interior of the Rad Disk™ maintains a filter protected sterile environment. Rad Disk™ uses a patented offset design that allows vertical stacking of cages so that adequate airflow reaches each cage. The filtered cage prevents contamination during and after irradiation, and during transport in and out of animal rooms. Because Rad Disk™ is constructed of polycarbonate plastic, it is autoclaveable. The Rat cage is 4" high and 10 ¾" in diameter, designed to fit into Gammacell 40 or Nordion irradiator loading chambers. Used as directed, Rad Disk™ prevents contamination of mice during the irradiation process even when irradiator is located outside of the animal rooms or facility. Rad Disk™ comes complete with a removable divider system which can divide the cage into 4 to 8 separate compartments, if desired, for irradiation. The cage can also be used without the dividers thus allowing the free ranging mice to receive more uniform irradiation exposure.