Loxmythe very well could be right (though I have a weird male end battery mini-cig that I've never been able to figure out what it is, and my 401 gear won't work with it)!
Your model could very well could be a just like the Health E-Cig. (I think it still is a good idea to contact the vendor in my OP and ask for sure). The Health E-Cig is not really a true 401, but called a 401 clone Model. It is also known as a EC502. There are posts here by people that have the Health e-cig kits that say they will work with the 401 attys/batteries. Here are the specs for them:
With the atomizer attached:
M 401 is 108mm
M 402 is 95mm
M 403 is 85mm
The atomizers for the M401/402/403 are identical, but their batteries are different in length and capacity.
M401 battery 200 mAh (about 2 hours use)
M402 battery 150 mAh (about 1.5 hours use)
M403 battery 100 mAh (about 1 hour use)
It might be worth finding an inexpensive Smoore (manufacturer) M40X series kit, as they are a good e-cig for a mini.
At a later time, if the 401 atomizer works with his INOCig01 kit, you could get a 401 to 510 adapter and get him 510 atomizers if he wants to keep the small battery size (batteries seem to outlast atomizers). Prosmoke.com actually has a good deal on batteries,
Replacement Parts - Replacement Battery - ProSmoke - The #1 Rated Electronic Cigarette - An Easy Way Quit Smoking and The Best Smoking Alternative but is a rip-off for atomizers ($12.99!). Litecigusa.com has the atties for $6.95
M-401/2/3 Atomizers and the smaller M403 batteries for $10.95
M403 Replacement Battery
Best deal is on the clone kits. Deal Extreme has the Health E-cig kits (M401 clone) and free shipping (expect it to take a while to receive it, but generally, they do a good job). Move your cursor over the pictures to blow them up large to compare your model. The packaging they show looks like yours, but who knows until you get it. You can't beat the price if that is really what he wants. Some of the kits come with a personal charging case (PCC) as well which is very handy for those little batteries since they don't last long. Here are 2 examples you can compare yours to:
$6.10 - Quit Smoking Rechargeable Electronic Cigarette with 7-Refills (Flue-Cured Tobacco Flavor/DC 5V) - Cigar Pipes and Cases
$9.21 - Quit Smoking Electronic Cigarettes with Chargers and 10-Refills Set (110~240V) - Cigar Pipes and Cases
It seems to be inexpensive, so you could get a few kits for some back up parts if you really think he's satisfied with the small size/cartridge of that little e-cig. At least he's willing to use it!