These black rubber, one-hole stoppers are specifically designed to fit 500 and 800 mL Kjeldahl nitrogen determination flasks.

• Excellent resiliency
• Very pliable stoppers
• Stoppers come with an 8mm-diameter hole

Stoppers have low free-sulfur content (¹/₂%), lower density than neoprene, and excellent resiliency and pliability. Both sizes come with an 8mm diameter hole.