I use it to refill 13ci tanks to 3k, it's honestly not that bad, but you definitely want to space out reps to prevent the pump from heating up. Initially, I had to tighten up the hose end, or else it would have started leaking at 2k but I'm sure most people would have known how to use a wrench. So far so good, lock your arms and pump with your legs and body weight or else you will not reach 3k.