The mouse pie restrainer can hold 11 mice at one time for uniform total body irradiation studies. This restrainer consists of only two parts; a base and a lid. It does not require any nuts and bolts so you do not have to worry about losing critical parts. Due to the unique design, the lid can easily rotate but cannot be lifted off of the base unless simultaneously lifted from two opposite ends, which mice cannot do from their individual compartments. It is especially easy to use and clean. The ventilated lid has a pie-shaped cutout that can be rotated about any base pie compartment in order to load or unload mice. The mouse pie restrainer is also commonly used by customers to place mice in a particular order for studies where pharmaceuticals are administered. The mouse pie restrainer is 8″ in diameter and 2″ in height. Individual compartments have been tested to restrain mice up to ~50g.