... no burning Specification of glass test tube stopper(mm) Φ 12 (9*13) Φ 13 (11*15) Φ 15 (14*17) Φ 16 ( 15*18) Φ ... core Φ 35 (33*38 )with china core Note: Φ 12, Φ 13 etc, means external diameter size of test tube, size in ... of glass test tube stopper(mm) Price ( USD) Φ 12 (9*13) 0.05 Φ 13 (11*15) 0.08 Φ 15 (14*17) 0 ... .13 Φ 16 ( 15*18) 0.16 Φ 16 ( 13*18 ) with china core 0.17 Φ 18 ...