The only thing different is the marine versions come hard anodized to prevent corrosion to my knowledge. These work fine if not in salt water. On these cast ones though be careful not to overtighten it onto the bypass (the bypass casting will break). We have a bypass eliminator billet part to solve that problem if you want to do away with the bypass. Also don't overtighten the pipe fittings into the casting as it will crack easily. We also make a billet bypass adapter to get around that problem. Cast one will work fine though if you're careful.