It's possible that they could cause some sort of nerve or blood vessel damage. There was a patient not too long ago who made his way into the ER because he tried to get some "oral satisfaction" with his vacuum cleaner. Needless to say - the suction force of a vacuum cleaner versus a HANDPUMP is quite astronomic - the man's penis was so engorged - his blood vessels in his penis contracted and left his member stuck in the vacuum extension tube.
Hand pumps can be hot but I really like the images of guys being milked while tied down by electric pumping machines that continue to pump to multiple orgasms until it's painfully dry. I'll try and post some pics.
Yeah, I'd like to buy one but when I look on line I get get a clue which type or model or design is best. Anyone got some good advice please? The more advice the better!