What matters on shift
Battery life first, a camera that dies before the shift ends is worse than none, so look for units rated beyond your longest day. Pre-record is the feature that separates serious units from cheap ones: the camera continuously buffers the last minute or two, so when you hit record you capture what happened immediately before, not just after.
Mounting decides whether it gets worn. Clips work on some uniforms and fail on others; a harness is more secure for physical work. Some units come with a docking station, and for a team that is worth looking for: one dock charges several cameras and offloads footage automatically at the end of a shift, instead of someone plugging in eight cameras by hand.
Offline, WiFi or 4G
An offline camera records to internal memory and nothing else. There is no network, no account and nothing to fail, and the footage comes off over USB at the end of the shift. For most single-operator use that is the right answer.
WiFi models add transfer without a cable, so footage moves to a phone or a laptop as soon as the wearer is back in range. 4G models go further and stream live over the mobile network, which is what a control room or a lone-worker setup needs: someone else can see what the wearer sees while it is happening.
Resolution follows the same logic. 4K gives you detail that holds up when a frame is enlarged, such as a face at distance or a plate across a car park. 2K records for longer on the same card and battery, and is enough for a general record of an interaction. Decide which of those two the footage is for.
Visible by design
Unlike covert cameras, a body camera is meant to be seen. Visibility is most of the deterrent, and it sets expectations for everyone in the interaction. For discreet recording instead, see wearable spy cameras.
Common questions
How long does one record? Typically eight to twelve hours continuous, depending on resolution.
Can footage be edited? Better units watermark and lock footage so it stands up as evidence.