As functional as this set is unique. Upon close inspection you will notice a "+" and a "-" embossed into the base vessels. Each of these signs indicate the different flow rates that the apertures will yield.Details:Set of 2Each, 2.5"H x 2"DiameterCapacity 2 fl. oz. eachFDA approved silicone o-ringHand burnished with FDA approved sealerWipe clean with damp clothSlight variance may occurDuctal concreteBacked with cork for tabletop protection• Each shaker is composed of a cap/plug which fits accurately and securely into each base thanks to very narrow tolerances as well as the compression of an FDA approved silicone O-ring. It is noteworthy to mention that the cap/plug only comes off if you are filling the shaker with salt or pepper. You DO NOT have to remove the plug/cap to shake your salt or pepper. The distribution of salt or pepper is facilitated by the different sized apertures which have been cast into the base.