NS Novelties Sinful line Door Restraint Straps Black. Pleasure comes knocking with Door Restraint Straps from Sinful Bondage. Made of sturdy and adjustable canvas straps, the restraints easily slip over door entryways, transforming any room into a den of punishment and play. Durable and hassle free, Sinful Door Restraints are compatible with Sinful Wrist Cuffs, sold separately, and are nickel free and safe to use. Materials canvas, steel.