Dave's portable HeNe is 1mW and you can see the beam on his photos...
As all laser beams.... they are more visible the stronger they are and the
more suspended particles in the air make them even more visible...
The one on eBay is the same 632.8nm wavelength as Dave's laser.
Big thanks to JimmyMCJimtheJim for pointing out that HeNe pointer on E-bay. I shopped victoriously.(won) Just waiting on the seller to give me a final shipping price. Should be around $67AUD. That's pretty good compared to what it probably costed brand new in the 1980s. ($1000+)
Message to Dave:
Please tell me what kind of money you had to fork out for yours. I know I got really lucky with this one.
I don't remember now. I had been bidding on them (and losing) every time I found one offered. However, IIRC I was VERY pleasantly surprised at how inexpensive I got mine for considering how high the bids were to which I lost others.