Laser 650nm
It is just a simple red (650nm) laser light, but dangerously strong. This is no toy for little kids. By night I can see it until about 200 m. Only the 2 outer pins must be connected with 5Vdc power or PWM. They consume about 30 mA. The laser emitter mates very well with a laser receiver or LDR. You can use the Hello World example sketch as an automatic switch.

http://www.banggood.com/100m-835-655mm-Tactical-Aiming-Red-Beam-Dot-Laser-Sight-Scope-With-Mount-for-Gun-Rifle-Pistol-p-1027717.html

Laser level pointer, Lidl 9.99, 2016-07-28