no serm is required with 677... if you run it as a stand alone then you would not need any pct... keep in mind that 677 need to be ran for a year continuously without cycling off... the very best quality 677 you can find is located here... https://www.sarmsx.com/nutrobal-mk-677
No pct required after MK-677. It doesn't affect your HPTA at all. You can literally run it any time, on cycle, off cycle, pct, whatever.....and idea.ly you would run it long term for about a year to reap all of its benefits
(PM me for a price list for Biotech Labs and 10% discount)