Check the listing for details. Red Rubber Stoppers Size 31 One Hole Pack of 5 Corks Bungs. Condition: New. Listed at 24.18 USD. Neoprene stoppers have better resistance to heat, ozone and petroleum based oils than red rubber but are less suitable for low temperature use. Premium High-Temperature Tapered Translucent Silicone Stoppers for Tubes, Bottles, & Barrels made from an FDA compliant compound. Ideal for use in Biology, Haematology, Food Science, Home Brewing, Barrelling Technical, Medical, and Hospital. Ideal for use in Biology, Haematology, Food Science, Home Brewing, Technical, Medical, and Hospital. High Quality 100% Natural Cork Tapered Stoppers. One of the most natural ways to seal objects and make them airtight, natural cork stoppers are food safe and unglued, perfect for a range of different storage uses & Hobbies including Perfumery, Terrariums and much much more. Natural cork stoppers are one of the.