1. Double Row Ball Bearing type: Double Row Ball Bearing type tension device gives you friction free smooth rotation of the apron. Higher circumference of the rollers prevent sharp bending of the bottom aprons which results in long life of the bottom Aprons.2. Aluminum Fork Type:WE provide Pressure die cast Aluminum fork for both Ring frame and speed frames, this is the most economical and effective tension devices when compared with dead weight type rollers. 3.. Dead Weight type: This the older version of tension Devises used earlier.