A superior grade of rubber that has softness, resiliency, and durability

• Size numbers are molded into the top
• All stoppers are 25 mm long
• Size 2 and above accept 6 mm tubing
• Approximately 454 g (1 lb.) per bag

Black stoppers are made of solid natural rubber that stays pliable over a long period of time. Ideal for use with non-aggressive or concentrated solutions. Stoppers feature a low sulfur content, and will withstand temperatures from –25 to 70 °C (–13 to 158 °F).