These racks offer complete protection for all your delicate and valuable stemware and tumblers from washing and handling to stacking, storing and transporting. Note Compartment Extenders cannot be added to these racks. Choose the correct dish rack 1. Measure the maximum diameter of your glass (stemware or tumbler) to determine the number of compartments. Measure the maximum height of your glass (stemware or tumbler) to the top edge of the rim to determine the compartment height.