use: Useful in chemistry laboratories for 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. Specification: 100ml / 19×3 100ml / 24﹒19×2 250ml / 19×3 250ml / 24﹒19×2 250 ml / 24×3 500ml / 19×3 500ml / 24×3 500ml / 24﹒19×2 1000ml / 24×3 1000ml / 24﹒19×2 2000ml / 29﹒24×2 3000ml / 34﹒24×2 5000ml / 40﹒24×2 10000ml / 50﹒24×2