This tool should be used as a guide only. Seaforce 60M may not be an exact match for Sea Grand Prix 660 HS by but we have given the closest match we can. Seaforce 60M should do the same job and have similar properties but you should always read the technical data sheets for both Seaforce 60M and Sea Grand Prix 660 HS to be sure. Please see any notes to see any major differences and call us on 01285 862132 if you have any specific questions.