Does the R4-RD record all four cameras at once?

Yes. It records front, rear, left and right channels simultaneously at 1080p, so one unit covers the whole vehicle.

How is the R4-RD different from a two-channel dash cam?

A two-channel cam covers only front and rear. The R4-RD adds left and right views, which helps with side impacts and lane-change disputes.

It stamps each clip with speed, location and route data, which can support your account of an incident.

It uses a microSD card, and with four 1080p streams you want a high-endurance card with a large capacity and regular reformatting.

It is more work than a single dash cam. You route cables to the rear and both sides, so a professional install is worth considering.

It records at night, but four 1080p channels mean smaller sensors and less low-light detail than premium single-channel cams.

At Best Buy, for $299.99, as of our latest check.

$299.99at Best BuyChecked Nov 12

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