>>81494462
The ones in your image are not very painful since they don't squeeze tightly, your nipples do get a bit sore afterwards, so in that regard it would be more painful to use nipple clamps for, say, 15 minutes and then pinch her nipples using your hands. If you want actual pain I would recommend nipple clamps that can be closed all the way so they dont leave a gap. There's probably some more extreme model with needles which definitely will be painful but in such case you of course have to consider they might cause an infection so make sure to disinfect each time before use. It's also possible to make things even more fun by using electricity, but for this you need to make sure to take care so the electric current will travel only through a single nipple, with no risk of traveling through the heart.