O-Ring Kit from Tantus Silicone. Tantus Silicone O-Ring Harness Set is compatible with any harness that takes an O-Ring. Set includes six different sizes to accommodate your Tantus Toy of choice. Do not use O-Rings on penis, this is for toy use only. Harness compatible, when O-ring is used. Safe for your body. Made from Tantus own unique formula of 100% Ultra Premium Silicone.Easy to clean. Eco-friendly, hypoallergenic, hygienic. Boilable, bleachable and dishwasher safe top rack. Diameter of rings from the smallest to largest 1.2 inches, 1.48 inches, 1.74 inches, 1.97 inches, 2.22 inches, 2.5 inches.