Black Rubber Stopper #1 1-hole (4mm). Top diam. is .748"(19mm). Bottom diam. is .551"(14mm). Height is .984"(25mm).
Approximately 63+ per pound.
Forensics Lab Supply Number 3731104.
Formerly Grau-Hall Corporation dba Grau-Hall Scientific.
NOTE: Unlike some inexpensive imported products, these stoppers are made to standard size and hardness specifications.