What is a cross clamp for a chemical experiment?

What is a cross clamp for a chemical experiment?
The lab iron stand is a common teaching equipment in the teaching of chemistry experiments in colleges and universities, and the cross clamp, being an integral part of the laboratory iron stand, mainly plays the role of fixing the test tube clamp and titration clamp. iron stand. Its safe, convenient and fast use is essential for the assembly of a complete set of experimental equipment.