Well, my dick is 21.5 cm now, and when I started it was barely 18 cm. I am not really doing any serious routine, but when I wank I kind of stretch and restrict bloodflow out of the penis, and I sometimes bend my semierect penis. It keeps the gains. I don't know if they will ever disappear, as my "routine" isn't problematic to keep up. At least the gains stays for some weeks (the longest I haven't been pulling and tugging). Also, it seems it improves my erections. If I don't do anything, then it gets weaker. Also do some contractions with the muscles that stops your urine flow. I do some in the morning. A nice erection is as important as 1 inch extra of anything.