A customer told us the original use for these Spartacus Butterfly Nipple Clamps was to keep fabric taut when sewing. While we can't claim to know their effectiveness on cloth, we do know what they do to skin.
Non-adjustable, Spartacus Butterfly Nipple Clamps are tight when you put them on and get tighter when you tug on the chain. We'd consider these a higher-intensity clamp, since these aren't adjustable like most other nipple clamps!
Butterfly clamps tend to work best when placed directly on the nipple, while other clamps like Spartacus Tweezer Nipple Clamps tend to work better when placed just behind the nipple. With a softer silicone pad inset, these clamps provide great hold and grip and don't risk coming loose during vigorous play.