use : Useful in chemistry laboratories in organic reaction or distill purification, usually cooperates with beaters、condensers and separatory funnels to compose various equipments to work. It could also used to install equipments for air reactions. It could install a more part when increases a interface, and is more convenient to use. Specification: Vertical four-neck flasks 100ml / 24﹒19×2﹒14 100ml / 19×3﹒14 250ml / 24﹒19×2﹒14 500ml / 24﹒19×2﹒14 1000ml / 24﹒19×2.14 1000ml / 24×3﹒14 2000ml / 29﹒24×2﹒14 angled four-neck flasks 3000ml / 34﹒24×2﹒14 5000ml / 40﹒24×2﹒14 10000ml / 50﹒24×2﹒