The TriLite MR3 is a low-profile 12V DC rotating beacon that drops onto a vehicle roof or dashboard and plugs into a DC adapter. Every current MR3 is a magnetic mount, so there is nothing to drill and nothing to wire.
Four models cover two decisions. MR3-12M and MR3C-12M run a 35 watt incandescent lamp. MR3H-12M and MR3HC-12M run a 50 watt halogen lamp. The C in the name means a coiled cord instead of a straight one.
Dome colors are amber, blue, green, purple and red. Velcro strips and a removable vinyl beam-glare shield come in the box, and the beacon turns at 90 to 110 flashes per minute on a belt drive.

What is the TriLite MR3 rotating beacon?

The MR3 is a compact rotating reflector beacon built for 12V DC vehicle power. It sits low enough to stay on a roof or a dashboard without catching on door frames or low clearances. A belt drive turns the reflector, which runs quieter than a gear drive and keeps the maintenance simple. The removable vinyl shield lets you cut the beam where it would otherwise bounce back at the driver. Plug it into the vehicle DC adapter and it runs.

Incandescent or halogen: which MR3 lamp should you choose?

The 35 watt incandescent models, MR3 and MR3C, are the standard choice for indoor and yard work where ambient light is moderate. The 50 watt halogen models, MR3H and MR3HC, put out more light and suit brighter surroundings or longer sight lines. The trade-off is current draw. Halogen pulls more from the vehicle supply, which is worth checking on a small battery or a long shift.

Straight cord or coiled cord?

Pick the straight cord if the beacon stays in one spot on the vehicle and the run to the socket is short. Pick the coiled cord, the C models, if the beacon moves between the roof and the dashboard or the slack would otherwise sit loose in the cab. A coiled cord retracts and stays out of the way. A straight cord is easier to route and cheaper to replace.

Roof or dashboard: how does the magnetic mount work?

The magnet holds on flat steel, and the included Velcro strips give you a second option where the surface is not steel or the beacon needs a fixed spot on a dashboard. TriLite designs the MR3 for both placements. Roof mounting gives the widest visibility. Dashboard mounting keeps the beacon clear of low-clearance trouble and is easier to reach. Note that no current MR3 model is a permanent mount.

What dome colors does the MR3 come in?

Amber, blue, green, purple and red, which is a wider range than most beacons in this size. Amber is the usual pick for general vehicle and equipment warning. The other four are commonly used to separate vehicle types or zones across a site. Color rules vary by site and jurisdiction, so confirm your own requirement before you standardize a color on a fleet.

Can you upgrade the MR3 to an LED bulb?

On two models, yes. TriLite documents its Mars 426013 LED replacement bulb for the MR3-12M and the MR3C-12M, the two incandescent versions. The halogen models, MR3H-12M and MR3HC-12M, are not covered by that documentation, so do not assume the bulb drops in. An LED swap cuts current draw and lamp replacement, which is the main reason fleets ask about it.

Rotating, flashing or strobe: what is the difference?

A rotating beacon like the MR3 spins a reflector to sweep a beam around the vehicle, so the signal itself moves. A flashing light switches on and off in place. A strobe fires a short, bright burst. Sweeping beams read well in open yards and across long sight lines. Flashing units such as the FF3 and FFLP are simpler. Strobes like the MS1 and MS11 cut through bright ambient light. Match the type to the site rather than the price.