These Japanese Clover Nipple Clamps With Bells are designed to increase in grip and pressure when pulled upon. The rubber pads of these clamps are textured for a firm grip, and curved to allow the clamp to bite upon the areola, leaving the nipple exposed for additional stimulation. Although the pressure applied by these clamps can be fierce, removing the clamps after some time will be more intense than when they were first on. 

Also, That bell! Perfect way to just add a little personality to your kink, or to always know where your sub is - like a pet (hint, hint)!