I was looking for a simple, small, single brightness LED flashlight. I have been using the wonderful Fenix E01 flashlights (now out of production) - 20 lumens, one AAA battery, foolproof on/off, Up to 20 hour battery life. I wanted a flashlight as close to this as I could find and came across these Energizer Keychain Flashlights. I read many of the reviews on this light and bought one to evaluate. My main concern from numerous reviews was the on/off switch. Some reviewers indicated it cannot be kept on, some indicated it would turn on accidentally in a pocket or bag and and the battery was always dead when needed. Other reviewers indicated the product design has changed several times over the years with respect to the on/off switch and how it functioned. None of the design changes changed the product name. There are no model numbers for these flashlights. The two I received recently (Feb 2022) cannot turn on accidentally in a purse, bag, or pocket UNLESS THERE ARE METAL ITEMS TOUCHING THIS ENERGIZER FLASHLIGHT. The on/off switch is a contact switch using the conductivity of your skin to turn the light on. The little metal disc embossed with a fingerprint is embedded in a polymer plate insulating the disc from the metal housing of the light. When you hold the light in your hand and touch the fingerprint disc, your skin completes the circuit between disc and body and the light turns on. The disk/switch does not move or "click". when you remove your finger the LED slowly dies down. The light will only stay on as long as you keep your finger on the disc. Pressure on the disc has no effect. It does not function by pressure only by contact. I took a piece of metal and touched the disc and the metal housing and the light comes on instantly, circuit completed. Now, sometimes when you hold the light and touch the disc it does not come on at once, only after a few seconds. Understand that human skin is not very conductive when it is dry, and conductivity increases as the skin moisture increases. Thus, in this dry winter weather the light may take several seconds to come on. I think that the dry skin of your hand and fingers become more moist when held against the metal for a few seconds. Moisture is constantly produced by the skin's sweat glands, and it takes only several seconds for the skin's conductivity to rise enough to turn the light on. A very slightly damp finger (even unnoticeably damp finger) is instant on. THIS FLASHLIGHT CANNOT BE TURNED ON WHEN YOU ARE WEARING GLOVES. If you hold the light inside your closed hand it will turn on. BUT IT WILL NOT TURN ON IN A POCKET, BAG, PURSE, OR ANYWHERE WITHOUT CONTACT WITH METAL OBJECTS (KEYS, COINS, POCKET KNIVES). IT WILL TURN ON IN CONTACT WITH WET OBJECTS OR WATER. If your pocket gets wet, it will turn on in contact with the wet clothing. And stay on until contact is broken. THIS FLASHLIGHT IS NOT WATER PROOF. The brightness is nice, good enough to search around inside a dark car, cabinets, your bag or pack, get around a dark house. It will illuminate the trees in my woods for some 20 feet or more. I can use it to navigate a trail through the woods at night. The 5 hour battery life means this light can be used intermittently for probably a few weeks or so, but not a good light for constant use. My single AAA Fenix E01 does not need battery replacement for several months, and I use it a couple dozen time a day for brief periods. I'm guessing the CR2032 batteries in this Energizer Keychain light may last a month with similar use. DO NOT USE THIS LIGHT ON YOUR KEYS! UNLESS YOUR KEYS ARE NOT METAL. I think it will work great on the electronic car keys, BUT MAKE SURE THE KEY AND ANY METAL CHAIN CANNOT SHORT AGAINST THE DISC AND GIVE YOU A DEAD BATTERY JUST WHEN YOU NEED IT TO WORK. With everything I've said, this light meets some of my needs for a very small, sufficiently bright flashlight (for 90% of my daily needs), with a fair battery life. I do recommend this Energizer Keychain flashlight. Replacing the two CR2032 coin cells requires a very small Phillips screwdriver to take out the 4 screws holding the back of the flashlight in place. Be sure that the replacement batteries have the same polarity as the battery removed from the light. So, some dexterity is needed to replace the batteries. Since I have a number of devices using these batteries (electronic car keys for instance), we always have fresh batteries stocked in our house.
