The CMG O4 is a super bright keychain light with a futuristic shape, rubber grips, and a simple but effective switching mechanism.
The high brightness LED is powered by a single CR2032 or a pair of CR2016 lithium coin cells (depending on LED color), and the unit is water-resistant because it has no external switch to leak.
The O4 is a good looking light, so you need not be ashamed to carry it around on a zipper, keychain, bag handle, etc.
The O4 is ready to go right out of the pack. To get a momentary burst of light, just give it a squeeze. If you wish for it to stay lit continuously, swing the small metal lever
on the top of the light downwards so the end of it covers the rubber button. This lever applies enough pressure on the button to light the LED without having to keep squeezing.
Swing the lever back to the top position to turn the O4 off.
To change the batteries, remove the phillips screw from the back of the O4, and use a flatbladed screwdriver to carefully pry the two halves apart. Be careful so you don't
damage the rubber gasket that seals out the weather.
Remove the old batteries, and insert the new ones, button side (-) facing towards the little circular thing with the LED on it.
Reassemble by aligning the two flashlight halves and firmly squeezing together; install the screw and tighten gently but firmly.
This diagram should help clarify things. The batteries are directly under that circular brown thing in the 3rd frame. Just dump them out (you may need to lift out the lower one
with your screwdriver or a good fingernail) and install new ones the same way. Flat (+) side down towards the small bottom disc, button (-) side facing up toward the larger disc
with the LED on it.
The O4 is a durable little light that also has a measure of water resistance as an added bonus.
When I ran over it with my Rascal scooter, the light came on when the tire was over it, and went back out when the pressure was relieved.
However, upon retrieving the light, the lever switch no longer functioned. It still squeezes on and off, but squeezing requires slightly more pressure than before.
If you value the ability to operate the light in hands-free mode, you probably don't want to step on it or run over it with the riding mower unless you happen to have
a screwdriver in your pocket.
A failure analysis I conducted revealed the true cause: it wasn't the flashlight at all; it was the batteries that warped slightly under the pressure.
Simply swapping the cells; placing the top cell on the bottom, was enough to restore proper operation. Replacing them with new batteries will also restore operation, but as I found
that was unnecessary.
12,800 peak mcd blue, 22,400 peak mcd white
Although I've had these things for awhile, I never did get around to testing them. The poor things have been largely ignored, but now their turn in the spotlight
has come. I will be using one as a daily carry item, and keeping the other one in relative comfort as a control sample.
I've found out that the CMG O4 will now be sold as a momentary-only light, without the spring steel clip for constant-on.
Any updates related to this review will be posted as they happen.
Small and discrete package
Nice looking flashlight
Waterproof (not just splash resistant)
Offers continuous-on with an innovative switch
Tools needed for battery change
MANUFACTURER: CMG Equipment
PRODUCT TYPE: Miniature keychain flashlight
LAMP TYPE: 5mm LED, choice of colors
No. OF LAMPS: 1
BEAM TYPE: Varies by LED color
SWITCH TYPE: Squeeze momentary and pivoting external lever
BATTERY: 1 CR2032 or 2 CR2016 lithium coin
CURRENT CONSUMPTION: Estimated to peak at 60mA
WATER RESISTANT: Yes
ACCESSORIES: Split ring
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