Euthanex LidsFeatures Lids fit standard EZ System cages No need to transfer subjects to euthanasia cage The Euthanex Lid system has become an industry standard. Simply by removing the water bottle from the wire bar cage cover and placing the Euthanex Lid over the host cage, you are ready to perform euthanasia. You no longer need to transfer animals. The lids are available in five sizes to accommodate virtually all plastic cage sizes designed for small lab animals.