Tg-500b are used in the houses, the ventilating pipes and the small buildings. 1. The ball diameter (body diameter) is 620mm (25inch), and the throat diameter (inner diameter) is 500mm (20inch). 2. There are three kinds of materials they are made of: (a) stainless steel, (b) vanes stainless steel+ others galvanized sheet, (c) vanes aluminum + others galvanized sheet. 3. The volume of air discharge is about 950-4000 cbm/h. 4. It is about 8 kg/set and the ubc bearings we use are from the usa. 5. We guarantee the usage for 15 years. 6. We can design and manufacture other sizes according to your demands. 650mm*650mm*200mm