Spartacus Nitrile Cock Ring Set in Black. these amazingly durable cock rings are made of 100% skin-safe nitrile. the same material used in hospital gloves. Nitrile c-rings are strong yet flexible. snapping back to shape after each use. And not to worry. they're compatible with silicone & water-based lubes! Set includes 1.25. 1.5 and 2.