These things are surprisingly better than I thought, and they can be powered up to 9v (as far as I tested them, with a potentiometer of course) and the dot the beam produced was huge and bright, but of course not powerful enough to burn anything.
Great deal! Cant go wrong at this price. As you can see from the pictures that I posted, Nearly every one of the 300mw Green Laser Pointer that I purchased produced a nice and bright red dot. No need to use a resistor if you have a clean and stable source of DC at 5V or less (i got a nice range of visible light from 2.9V - 6.2V). I ran these straight off my DC power supply to a breatboard at 4.8V. I kept about 20 of them at full power for over two hours and they held up just fine. This is such an awesome laser level! It is sleek and deluxe. It looks good, it feels good, and everything about it screams that it was well thought out, upscale, and high-quality.
I was rather surprised buy the quality of these at this price but they are actual red dot LASERS,not just red LEDS mine seem to be brighter at 3.6 volts but I haven't ran them for long enough periods to tell you if they will get hot or not.This 650nm laser diode is an industrial electronic component and used for as Industrial testament, Lab, DIY.It is precise and sensitive optical instrument. Before carrying on some laser DIY activities, please read about the technical information first and protect your eyes before laser ray. Be sure the operator has experience in optics DIY or testing.
Great Laser Sight for the price, all 5 of mine tested successfully and put out nice red beams. Note that these cannot focus very far (wasn't able to discern the beam after about 10' or so, and focus was extremely rough further than a foot or two), and are fairly low power. These are almost exactly 1/4" in diameter, and the front will fit nicely into a tube or opening of that size. It only has two controls, which I liked for simplicity. It has a button on the top, which toggles between cross-hairs, horizontal line, and vertical line. The second control is a switch for balancing, or laser stabilization. In my video, I purposefully unbalance the level, to show how nicely it balances once you use the balancing switch.
This is a very handy, well made piece of equipment. It has actually six modes: plumb line, level line, cross level and plumb line, and straight edge lines similar to those three modes for using lines at angles to plumb or level. For level operation it warns you when you are not within the auto-level range, which is a pretty generous range. The laser is very bright, so it is easy to see both indoors and outdoors, but be careful not to blind yourself or others.