Check the listing for details. Rubber Stopper - 22 Pcs Solid Rubber Stoppers,11 Assorted Sizes 000# - 8# Tap.... Color: Black, Condition: New. Listed at 14.56 USD. Rubber Stopper - 22 Pcs Solid Rubber Stoppers,11 Assorted Sizes 000# - 8# Tapered Lab Seal Rubber Stoppers. Widely used: These rubber stoppers are suitable for laboratory and industrial use. Solid Rubber Stoppers: These black stoppers are made of high-quality rubber, which is very durable, not easy to deform, and has good sealing performance.