When buying a stainless steel product for a boat, there is always the question "Will it Rust?" One way to check the grade/quality of the stainless steel is with a magnet. If the magnet will adhere to the product, it will rust. Take for example a hose clamp. The band of the clamp may be of good quality and the magnet not stick or adhere; however, the adjusting screw may be of poor quality and the magnet will stick. All good quality/grade stainless steel is non-magnetic----bolts, screws, nuts and plugs. If you are going to use it in a boat, make sure it is non-magnetic.