316 stainless steel is a relatively uncommon and relatively expensive stainless steel alloy containing 2% molybdenum, making it much more corrosion resistant than regular 304 stainless steel. Regular 304 SS is used in almost every stainless steel product you will find in residential or commercial products because it's very strong and very corrosion resistant, but it does not hold up well to repeated chlorine bleach exposure or hard water. That is where 316 SS shines.