This tool should be used as a guide only. Se-lett Orange 1L may not be an exact match for Interlac 668 by but we have given the closest match we can. Se-lett Orange 1L should do the same job and have similar properties but you should always read the technical data sheets for both Se-lett Orange 1L and Interlac 668 to be sure. Please see any notes to see any major differences and call us on 01285 862132 if you have any specific questions.