1. Electromechanical products that have been used and still have basic functions and certain use value;

2. Mechanical and electrical products that have not been used but have been stored for too long and have exceeded the quality guarantee period;

3. Mechanical and electrical products that have not been used but have been stored for too long, and the parts have obvious tangible loss;

4. Electromechanical products with mixed new and old components;

5. Large second-hand complete sets of equipment.