The Hawkeye Pro Slim Borescopes .165? (4.20 mm) from Gradient Lens Corporation is a Borescope with Viewing Angle 0 Degrees, 90 Degrees, Field of View(FOV) 42 Degree, Operating Temperature -20 to 120 Degree C, Probe / Insertion Tube Diameter 165 Inches (4.20 mm) (Scope), .188 (4.80 mm) (Mirror tube), Probe / Insertion Tube Length 7 Inches, 12 Inches, 17 Inches, 22 Inches. More details for Hawkeye Pro Slim Borescopes .165? (4.20 mm) can be seen below.