The kit includes:
The laser power supply, ballast resistor, and brackets are wired together so that all you need to do is attach them to a baseplate (this is needed to support the brackets at the correct distance). You will need a source of 21 to 31 VDC at less than 350 mA (positive to red wire, negative to black wire). This can be a DC wall adapter (available from places like Jameco and MCM Electronics for under $10), a homeless laptop power pack, or a home-built power supply (schematics can be found at Adapters for DC HeNe Laser Power Supply Bricks. Jameco lists several suitable DC wall adapters. I tested the laser with one rated 24 VDC at 500 mA max (the laser actually draws about 225 mA from the supply). This particular model was regulated but that isn't necessary. The SMPSPWR1 switchmode power supply listed elsewhere on this page will work but is just a wee bit of overkill if all you are powering is the laser! A power switch and indicator light are optional (not included).
I will provide a DC wall adapter from Jameco for an additional $25 if you insist, but you can get it cheaper directly.
The laser power supply has an enable input (yellow wire) which turns the laser on when grounded. For details, see: Assembly and Operating Instructions for HENELSK1 Helium-Neon Laser Kit. There is a drilling guide at HeNe Laser Mounting Template. Print this at 100 dpi or at 96 percent in PhotoShop and the holes should line up properly.
The laser tube has a divergence of around 8 mR - the beam is about 1 cm at 1 meter distance. The beam is TEM00 but the outside surface of the output mirror is curved to expand the beam (non-removable). A positive lens with a focal length of between around 2.5 and 6 inches can be used to produce a very well collimated beam - equivalent or better than is possible with any bare tube.
For an additional $5, this kit is available with the tube and power supply attached by Alden type connectors which make it easier to use the components for other projects. Order HENELSK1-A.
All of the components are from supermarket barcode scanners that were removed from service due to upgrade, are in excellent condition, and fully within manufactuer's specs.