stonylab Solid Rubber Stoppers (Black), Tapered Plug for Sealing Test Tubes, Flasks and Laboratory Glassware, 10-Pack, #6

Ensure secure airtight seals for laboratory flasks, test tubes, and condensers during laboratory processes or sample storage Available in multiple sizes to fit diverse laboratory apparatus; please verify dimensions pre-purchase for compatibility with standardized equipment (±1mm measurement error) Maintains flexibility and sealing integrity without hardening or cracking Note: these rubber stoppers are NOT food grade 1-year coverage period for your peace of mind, if received damaged, please let us know and we will solve it promptly