5mW 532nm Focusable Green Laser Pointer Pen,$13

Specifications: Features: Constant Wave
Output Wavelength: 532 nm
Output Power: 5mw               
Beam Distance: 500-6000m
Working Voltage: DC 3.2V
Trigger Voltage: DC 2.8V
Working Temperature: 0℃～+40℃
Storage Temperature: -10℃～+50℃
Power: 2 x AAA Batteries
Dimension: 160 x 14mm/6.3 x 0.55in(L x Dia.)

http://www.lasersman.com/red-laser-pen-650nm-5mw-mid-open/