O.K. I am a newbie and doing my best to research information on post cycle therapy (pct). One of my biggest questions are about all the AI's that are available. There is letro, liquidex, arimidex, and exemestane. It sounds like they are all chemicals that protect against gyno. From researching them it sounds like letro is the strongest and should be used if you already have gyno. The others all seem the same to me. Are they the same? Should some be used during cycle to prevent gyno? Should some be used during post cycle therapy (pct)? What are the differences if any. Any help would be greatly appreciated.