Dam I have a vague understanding so hopefully someone else chimes in. 19 nors which tren, decca and npp fall into produce prolactin. Which if it gets to high can kinda act like high estrogen and can effect you and produce gyno, limo dick and mood swings. So by taking an anti prolactin like caber or prami you essentially treat prolactin like you would use adex or aro to treat estrogen. The only thing is prami makes you sick and the dose is like .25 mg, takes awhile to build tolerance. So I'm running high tren, med test and low mast. My estrogen is in check but my dick has been kinda iffy here and there. Decided that dosing on pin days is best bet until bloods get drawn next month. Now this is just my understanding. I'm sure I got some of it wrong. Best bet is to read the wiki page in side bar and also do your own research.