Corning® lids are made of rigid polystyrene except where indicated. All lids have a corner notch on the A1 corner (except where indicated) to correspond to the corner notches found on all Corning® microplates. The Universal Lid without a corner notch (Cat.No. 83-3098) does not need to be oriented in any particular direction to be placed on Corning® plates. The lid also has a shorter skirt than standard lids. The black Universal Lid (Cat.No. 83-3935) is suitable for fluorescent and other light sensitive assays. The DMSO-resistant cyclic-olefin lid (Cat.No. 83-3085) is tinted amber in color for light-sensitive assays and is 100% DMSO-resistant. The sterile lids are sterilized by gamma radiation.