Bullet cameras are shaped like cylinders, and get their name from the fact that they resemble bullet cartridges. Bullet cameras come with weatherproof housings and are often used as part of outdoor CCTV surveillance systems.
Most bullet cameras have a fixed 4mm lens. A 4mm camera lens lets you to see facial features out to approximately 35 feet. A 4mm lens allows provides about a 70° viewing angle, which is the widest angle you can have without suffering picture distortion.