They are inexpensive; for this reason they are commonly used in systems that require a low price. There are three series available that differ according to their wavelength:
LC-LMD-525-120-01-A: Dot lasers at a wavelength of 520 nm. Despite the perceived brightness, this module is assigned to laser class 2. Thus, it has an output power of <1 mW and can be operated comfortably with a voltage between 3 - 6 volts.
The LC-LMP-635 series is focusable and is available as dot, cross-hair, or line laser. The modules have an output power of 3 mW; the wavelength is 635 nm.
The striking feature of the LC-LMD-650-02-T60 dot lasers is the surrounding temperature that may be as hot as up to 60 °C without affecting the properties of the laser module. Others begin to sweat at 20 °C. The module falls under laser class 2 with < 1 mW and is so small that it can be integrated into small systems as well: With a length of 11.5 mm and a diameter of 6.2 mm, it is comparable to the cap of a retractable pencil.
More Information: http://www.lasercomponents.com/de-en/lasers/laser-modules/low-cost-oem-modules/