PROS:The green laser is very bright. It is highly visible at 50 yards in bright sunlight. Easy to zero and keeps the zero after 800 rounds. Nice and compact. The tactical light is bright enough to enable target identification in the dark.CONS:Laser light would sometimes not switch on. Had the C5L for less than a month. First time I encountered this problem was after I used the C5L for about 1.5 hours in the shooting range. When I got home the C5L would not activate. I thought that maybe the battery that came with it might already be drained. So I changed the battery to a new Viridian battery. I made sure the battery cap was screwed in correctly and all the way in but the problem persisted. Right after I changed the battery the C5L worked. After practicing with it for approximately 10 min the laser refused to activate again. I've read that it may be caused by the battery cap not being screwed all the way in. So I made sure that the battery cap was all the way in and for a while that fixed the problem. After another 15 minutes the problem recurred. The battery cap was still screwed all the way in, so I tried to loosen it a bit and the C5L started working again. Every so often the laser will not activate. 25% of the time when I push the "ON" button the laser will not activate and I have to fiddle around with the battery cap to make the C5L work. This might be a defective unit so I'm returning it to Amazon for a replacement. I hope the next one is more reliable. I will update this review when the new unit arrives.--* * * * * UPDATE * * * * *2nd Unit (Replacement for the above) Serial # 36310Received the replacement unit last week.PRO: As always tactical light is very bright, can easily illuminate dark room at night. Strobe function is disorienting. Green laser is very bright and highly visible. Very good for fast shot placements, and tighter groups.CONS: Upon receipt of the replacement unit, I installed fresh batteries. Installed the cap carefully and screwed it all the way down. The first sign of a problem showed up a few seconds after installation. I am right handed so I use the right activation button. When I pushed the right button I noticed that sometimes the laser will not activate or if the laser is already on it will not deactivate. In contrast, the left button worked perfectly. I made doubly sure that the battery cap was screwed all the way in. I kept clicking on the right button for several minutes with varying degrees of pressure with the same results. I can feel the soft click but the laser sometimes will not switch on or it will not switch off. I thought that maybe because it was a brand new unit the problem might go away after it has been used for a bit. I hoped that maybe some of the kinks might be ironed out if I bring it to the range and fired a few hundred rounds. I did just that but the problem persisted. Out of 100 pushes, the right button failed to work 38 times. The left button worked 100% of the time.Called Viridian customer service. They were very helpful. The tech told me to make sure that the battery cap was screwed all the way in . The tech said that I should not be able to see any part of the rubber O-ring between the cap and the unit. She said that the cap must be screwed in until I can no longer see the rubber O-ring. I checked and told her that I could not see any of the O-ring but the button problem persisted. The tech told me that they were going to repair the unit but I opted to return the unit to Amazon for replacement. I paid $250 for the C5L and I expect to get a brand new unit that works right out of the box without any defect.* * * * Amazon customer service is EXCELLENT! Hassle free returns for defective merchandise. I have been a very satisfied customer since 2006.--* * * * * April 8, 2013 - UPDATE * * * * *3rd Unit (Replacement for unit # 2) Serial # 34721The 3rd unit arrived March 28. I installed it the next day. Worked great after installation, the 2 activation switches worked perfectly. The green laser was crisp and bright. Went to the shooting range twice (Mar. 30 and Apr. 3) and fired 200 rounds of regular load of .40S&W each trip. After the second trip the laser point developed a green haze surrounding it. When the laser is 5 feet from the wall the hazy disc is 4 inches in diameter. (See uploaded pictures) This problem persist even after I've cleaned the laser's lens with a moistened cotton swab as instructed in the manual.I really like this laser because it's very bright and holds a zero well. However, I already had 3 units sent to me and all 3 units had some sort of defect. Two of the units had defects upon installation and this 3rd unit showed its defect after about 3 hours of use in the shooting range. Something is wrong with Viridian's quality control. As before I called Viridian customer service and the tech advised me to send the unit to them for repair.I was thinking of returning this to Amazon for a refund but I've already invested on a TacLoc holster for the C5L and a pack of Viridian batteries. I'm going to call Amazon customer service and see what solution they can offer.--* * * * * May 1, 2013 - UPDATE * * * * *4th Unit (Replacement for unit # 3) Serial # 40485Amazon offered to send a 4th replacement (Great customer service!). Immediately after installation I tested the 4th unit. It worked fine. LED light and green laser worked. The right and left activation buttons worked 100% of the time.Brought it to the range a few hours after installation. After I fired 10 rounds of .40S&W factory target load, I noticed that the right activation button started to act up. Sometimes (1 out of 10 to 12) when I push the button it will not activate the laser. Or if the laser is already on, pushing the right activation button will not turn the laser off (same problem with Unit #2 above). The left activation button continued to work flawlessly. At the end of that first session (after 200 rounds fired) the problem with the right activation button persisted.Three weeks later (after 600 rounds fired) the right activation button fails to activate or deactivate the laser 10% of the time. The left activation button works 99% of the time. The LED light is still very bright, perfect at night. The green laser keeps the zero perfectly and helps greatly with target acquisition and shot placement.I decided to keep this Viridian green laser sight even though there are problems with the activation button for the following reasons: 1) The green laser is really impressive, have not seen a laser brighter than this. 2) Helps improve my shot grouping specially, during rapid fire.*** Work around for the erratic function of the activation button: 1. Get the Viridian Tacloc holster with ECR system. 2. Pre-set the Viridian laser/taclight to the mode that you like. 3. Activate the laser/light. 4. While the laser/light is still on, slide your gun into the TacLoc holster (the laser will switch off while in the holster). 5. The instant gun leaves the holster, the laser/light activates automatically.BOTTOM LINE: 1. Green laser very visible outdoors at 50 yards even in bright sunlight. 2. LED light - bright enough for its size, great strobe function 3. Reliability issues with the activation buttons-* * * * * Amazon customer service: the BEST !!! Without equal!! They went out of their way to make their customer happy. Thank you.