The 112mm Clear Protective Filter for Cine-Servo 17-120mm T2.95 Lens from Canon is a simple, clear filter with a 1x filter factor and is intended to provide general protection for a Canon CN7x17 KAS S Cine-Servo 17-120mm T2.95 Lens with an Arri PL Mount or a Canon EF Mount. This optically clear filter does not affect overall image quality while helping to reduce dust, scratches, moisture, and other elements from damaging your lens.