Surveillance cameras are a common physical control used to provide visibility into the security of premises, allowing the detection of unauthorized or unusual activity without engaging in physical confrontations. They act as both a deterrent and a means to gather evidence. Bollards are designed to stop vehicles, not for surveillance purposes. Keypad door locks are access controls but do not necessarily provide visibility or detection of unauthorized entry. A mantrap controls access to secure areas but generally does not provide visibility of the area beyond its confines.