I think really it all depends on what your running along side the masterone for me if I'm running test prop or tren ace or shorter ester compounds then I'll throw in masterone P just so I can pin it on the same schedule as the others... if I'm running longer ester stuff like test e or something of that nature I'll throw in masterone E..at least for me I personally feel they work the exact same just diffent kick in times.. mas p being quick and mas e taking a few weeks to hit..