KRAUS KGU-434B Quarza 33 inch Undermount 50/50 Double Bowl Granite Kitchen Sink in Black Onyx. Beautiful and versatile, Quarza granite kitchen sinks are made from quartz composite material that offers the elegant look of natural granite. With gently rounded corners and smooth easy-to-clean surface, these sinks add elegant style to any kitchen. Dual mount design allows you to install as undermount sink or drop in sink with any kind of countertop. Durable sink for kitchen stands up to impact, scratches, and shock, and is colored all the way through to resist fading. PLEASE NOTE: Although KRAUS quartz composite sinks are heat resistant, placing hot items right from the stove or oven directly into the sink may cause surface discoloration. Consider using a trivet or rolling mat for extremely hot items to avoid potential damage.