This was an awesome buy! If you like yours or your lover's nipples nice and hard and *****, this is the perfect product! It's easy to use and the O-rings work very well. We loved that it included several sizes of O-rings so we were able to find a size perfect to keep her nipples standing ***** for as long as we wanted! We found it works better if you get the ****** hard to start with, and start with the larger O-ring and work down to the smaller ones. My girlfriend LOVES them and says they make her nipples twice as sensitive as usual! I can just barely brush the tips of her nipples when these are on and her entire body quivers! We use these during foreplay and ***, and have combined them with vibrating ****** clamps. Now she really gets WET!! So if hard, sensitive nipples are what you're looking for, I would highly recommend these!!