Originally these pliers have a veterinary function but of course Mister B sells them with a different purpose in mind :-).
We don't castrate rabbits; we use them for nipple play. Use these pliers to stretch open one of the 100 small rubber rings and put them on your nipple as you can see demonstrated in the other picture. The further back you place them, the heftier it gets...
For an even better (or worse - depending on how you look at it) result, may we suggest that you first hardly suck or pump your tits? When you've vacuum-sucked your nipples which therefore are more pronounced, the ring has more tenderized flesh to squeeze into.... yummie!
One bag with 100 rings is included in this set, and you can buy bags with 100 spare rings separately.