Dayco's Automatic Belt Tensioner features a patented "flat spring" design that's engineered to provide less operating range variations in tension. This reduces the risk of premature accessory bearing failure due to high tension when a new belt is installed. It also lessens the risk of belt squeal and slippage, or poor accessory performance caused by low tension after the belt begins to stretch and wear. A Teflon strip wound within the spring resists abrasion. The flat spring itself is coated to resist rust.
Other superior design features:
Heavy-duty cast aluminum spring case resists cracking and fatigue
Steel locator pin and pivot tube (where the application demands)
Heavy-duty cast aluminum arm offers additional strength and less distortion
Thermoplastic rubber "spring slot plug" keeps out harmful contaminants
Zinc coated mounting bolt (where included) resists rust, and is concentric for a more even degree of constant tension