This tool should be used as a guide only. Jotamastic SF may not be an exact match for Interline 320SF(THA320/321) by but we have given the closest match we can. Jotamastic SF should do the same job and have similar properties but you should always read the technical data sheets for both Jotamastic SF and Interline 320SF(THA320/321) to be sure. Please see any notes to see any major differences and call us on 01285 862132 if you have any specific questions.