Nasty Nipple Play

I have acquired a entire lot of fresh fucktoys to play with, and I need a willing subject to test them on. Fortunately for me, this one is just stringing up around for my amusement! Its always good to keep a slave around for purposes such as these, and he is only too willing to be my test subject for my first lot of new toys - nipple clamps! I have several to choose from - how will he hold up under pressure?!