There is a glass piston at the lower end of the acid burette, which can be filled with acidic or oxidizing titrant, but cannot be filled with alkaline titrant, because the alkaline titrant can make the piston stick to the piston sleeve, making it difficult to rotate.

The basic buret is used to hold alkaline solution. Its lower end is connected with a rubber tube. Glass beads are placed in the rubber tube to control the flow of solution. A pointed glass tube is connected to the lower end of the rubber tube. Any solution that can react with the rubber tube, such as potassium permanganate, iodine and other solutions, cannot be put into the basic buret.