Some people get what look like love bites on. But you need to leave these on for a shorter time if you want to avoid that.
The usual way for cupping is with glass balls where a vacuum is set up by lighting a little fire inside the cup before placing it on your body.
With this system, a reverse air pump is used to take out the air for the necessary suction.
Those that would buy these would know all the ins and outs anyway.