I bought these to use in conjunction with other nipple clamps that I have. I previously bought the circular clamps with teeth and my plan was to attach those first and then clip these onto the part of my nipples that stuck out from the clamps. All fine and good with my cock waiting erect for some attention, pre cum leaking out of the tip when I tried to attach the cordless vibrating clamps. Small problem but no problem, when the jaws of the vibrating clamps wouldn't fit over my nipples. So I took off the rubber protector and tried that, still too narrow. I had to bend the jaws apart and they now fit perfectly. Having the rubber guards off means that the 'crocodile' like metal clamps (with teeth) now bite in really achingly well and I can almost cum without touching my cock the feeling is so ecstatic. These are now given regular use and with the weight of the casing they swing and pull on my nipples really nicely. I think they are an excellent addition to any nipple play fans' 'tool box'..