The M40C is made by a new company called SunwayLED whose lineup currently consists of tactical-style flashlights. Up the front the bezel is mostly smooth with tiny crenellations which let light shine through when its placed face-down. The bezel itself seems to be adhered to the head and not easily removed. Behind the bezel sits an toughened ultra-clear AR-coated glass lens which provides good light transmission and durability. Red and blue colored LED's line the lip of the textured aluminum reflector. There are six of each color placed alternately. The main reflector cup is nicely finished with consistent textured surface and nicely polished with no noticeable flaws. Sitting at the bottom of the reflector cup is a perfectly aligned MC-E LED. The exterior of the head has a series of cooling fins which run about half way down its length. Right behind these is a magnetic control ring used for mode switches. Subtle tactile feedback is provided by this ring at each selected position though there aren't any visual indicator markings printed on. There is also a red LED battery indicator on the side of the head which will steadily light up when battery level is low, and starts blinking when it's critically low nearing depletion. This battery indicator light is not very bright and doesn't distract during use. Looking from the rear, the head shows a sealed plastic case, bearing only the spring-loaded brass contact point to the battery pack.

The second of two part making up the M40C is the battery tube which houses two 18650 or four CR123 cells in parallel configuration. There will undoubtedly be comparisons to the EagleTac M2 series, and indeed they do feel almost identical in-hand. Though overall, with the head screwed on, the M40C feels more compact and balanced without being too heavy at the front end. Inside the battery tube is a battery holder which hold the cells nicely in place. The mechanical switch module is part of the battery holder as well. Threads between the head and battery tube are cut very cleanly and finished nice and smooth. They are of the "square cut" variety which is supposed to be more durable. The M40C is finished in a dark gray Type 3 anodizing with a very subtle brown hue. There is no separate tail cap though there is a section holding the rubber switch cap in place which is screwed on from the rear. Under normal use, there is no need to remove this part. The rubber switch cap sits flushed within the battery tube so the M40C is able to tail stand without problems. A reverse push button switch is used in the M40C so momentary activation isn't possible. Switching mechanism has an average amount of tension and travel before fully engaging. Once engaged, the switch provides a very audible and tactile click.

If you're unfamiliar with any of the terms used in this review, click here for explanations on common flashlight related vocabulary.

The M40C has a total of five output modes. There's Low, Medium and High output levels for white light. The red and blue modes only have one fixed brightness level each. Switching between either of these output modes is as simple as rotating the magnetic selector ring. Starting with the ring at its maximum counter-clockwise position, turning it clockwise will cycle through in the following order:

Low > Medium > High > Blue > Red

The main beam profile produced has a narrow hot spot but has a rather wide, softer corona as well. There's a minute dark are right in the middle of the hotspot, which is fairly common with MC-E LED powered lights. Apart from that, the beam is free from artifacts. Beam color temperature of the while LED is almost pure white, but slightly cooler when compared to sunlight white. The red and blue led clusters produce a wide flood-style beam and it also rather dim compared to the primary white output levels. Runtime provided by the M40C is just a hair below average. Regulation is maintained steadily with all battery configurations. On 4x CR123 cells, the light will start to blink once batter level is critically low as can be seen on the runtime graph on High mode. On protected 18650 cells, the protection circuit kicks in and light turns off abruptly. Though but the battery indicator LED on the M40C's head does light up about 15 minutes prior to this as a warning which is nice.

The Good - Simple control interface for mode mode changes. Relatively compact and well-balanced weight for a 2x 18650 powered light. Good regulation on all output modes.

The Bad - Runtime could be better. Red and blue light could have limited usability if you're expecting high output levels as it's primary white LED.

The Relative - Beam has an almost pure white color temperature. Red and blue light output option. Uses a reverse push button switch. Is able to tail stand.