SimplyCopper 15" Round Copper Bathroom Sink -- Undermount or Drop 15 elegant round bowl design, created of 18-gauge copper which is hand-hammered to provide a rustic antiqued look. This copper sink can be used as either a drop- in or an under mount. Outside Dimensions: 15" x15"; Inside Dimensions: 13" x 13" Drain Opening: US standard 1-1/2" 18 Gauge Copper Shown in Aged Copper Installation: Drop In / Under Mount