So how does it work? Is this 100% safe
Pumping works by drawing in more blood into your penis, this expands it to its fully erect state, if you stay in for 20 mins (as a beginner) more blood is forced into the penis which expands it size, this is temporary.
But overtime if you do it everyday for several months your penis tunica (areas that fill with blood) will have expanded therefore your penis size will increase.
It is only dangerous if you use too high a pressure (you will know when this is, it hurts a lot)
When pumping stay in your comfort zone, but you should be able to feel it.
Cock rings after are safe but take them off before you go to sleep or whenever you have finished.
Clamping is more dangerous because if constricts blood flow but in short session with a 5 min break in between it is good for cementing gains. (2 x 5min)