The wrong hose for your application can make for a smelly situation... literally. First, know your size. Marine sanitation hose is available from 5/8 up to 1-1/2 inch diameter. Determine the size hose you'll need (and any clamps too) before you buy. Marine sanitation hose also comes in a variety of colors including white with a blue stripe which may be an easy identifier for you while you are in the bilge one day! Wire or PVC wire reinforcement is also a choice to consider before you buy.