NS Novelties Sinful Black Ankle Cuffs. Sinful has been the name in affordable playful kink black. Now, Sinful just made sexy a little bit sexier! NS Novelties is excited to introduce Sinful: Black. Everyone has favorite collection is now available in a stunning midnight black finish while continuing to deliver the quality you expect. Black, nickel free anodized hardware, aesthetically striking embossed vinyl, and lined in soft yet durable liquid play friendly neoprene. Product materials Vinyl, Neoprene.