According to FDA requirements:
POLICY: In keeping with this recognition of a hazard and the advice given, the Center for Devices and Radiological Health (CDRH) will object to any intentional exposure of the public to hazardous levels (1.e., greater than Class I levels) of laser or collateral radiation (light) from this type of equipment. Further, the CDRH will object to any instructions or promotion of Class II or IIIa demonstration laser products (projectors, scanners, shows, etc.) that do not adequately warn the user to prevent such exposure.
Class I audience exposure levels.
Only Class I levels of laser radiation have no known hazard and these are the only exposure levels that are considered safe for direct exposure of people. Exposure of the audience to levels in excess of the Class I limits is not to be promoted or encouraged in any way.
Class II warning:
CAUTION Laser Radiation (or Light)
Do Not Stare Into Beam
Class IIIa warning: DANGER Laser Radiation (or Light)
Avoid Direct Eye Exposure
These levels are hazardous to the eyes. No direct or reflected beams may be directed into audience areas or used to scan the audience in any way. A projector certified as Class II or IIIa cannot be used for audience scanning unless the projector is equipped with an adequate scanning safeguard which will prevent scanning above the Class I limits and adequate user instructions for achieving the Class I levels are provided.
As an example for BS1000S with CT1 switch:
Superior design, premium materials and quality craftsmanship make Beamshot the best value available in Laser sighting Systems
BEAMSHOT Critical Design Components
1. Front Cap - Flat glass window lens with anti-reflective coating to ensure better laser output and to protect against dust,powder and smoke. The o-ring sealed lens is waterproof and easy to clean.
2. Laser Module - To integrate optic, laser diode, and driver circuit into a patented solid brass structure for the best shock resistance and heat sink consideration.
2.1 Collimating Lens - Double sided aspherical plastic lens which provides better laser collimating and long distance visibility.
2.2 Laser Diode - 670nm wavelength for standard brightness 650nm wavelength for 5 times brighter (SuperBeamshot) 635nm wavelength for 10 times brighter (UltraBeamshot)
2.3 Driver Circuit - Single chip APC (auto-power-control), controller on board to perfectly stabilize the laser. This will maximize the laser's lifetime and battery hours while minimizing the size.
3. Main Body - Constructed of aircraft aluminum 6061T6 with matte black or silver finish.
4. Silicon Cushion - Designed to protect the laser module from the powerful recoil.
5. Springs and Caps - Strong steel springs for better support and better electrical contact.
6. Battery - Popular CR123A lithium battery provides 20 hours continuous on usage.
7. End Cap - 8.1 Positive contact PCB with reverse pole protection structure. 8.2 Seal ring for water proof.
8. Pressure Switch - Be-Cu spring with gold plating which can withstand more than a million times contact.
9. Removable Elastic Band - Elastic band which allows you to position the pressure switch in any area on the handle of the weapon which is most convenient for you.