There are two important elements that you'll see on specs for stainless kitchen sinks: chromium and nickel. They enhance the quality of the steel, giving it strength and corrosion resistance, which is essential to the function of a kitchen sink.
Gauge represents the thickness of the stainless steel kitchen sink. Gauge ranges from 16" to 20" thickness. We recommend 16g sinks, since they are going to be the most durable option, and will most likely outlast your kitchen. Stainless sinks are usually labeled in a ratio like “18:8,” which refers to the amount of chromium and nickel contained in the steel. In this case the steel is 18% chromium and 8% nickel.
The higher the percentages of these elements that are present, the better the grade of stainless steel. The series number generally designates the grade of the steel. Stainless steel sinks are usually in the "300" series (specifically 304) because they are made from good quality steel with 18:8 to 20:10 chromium/nickel content.