- Heavy glass, without side tubulation
- ASTM Specification E 1406, Type I
- With capacity scale
250 mL flasks take rubber stopper No. 6; 500 mL flasks take No. 7; 1,000 mL flasks take No. 8; 2,000 mL flasks take No. 9; 4,000 mL flasks take No. 12. Flasks are fabricated from molded heavy wall for strength and have a beaded bottom surface that prevents scratching and slippage for additional safety.