Hi Shane. Do you have a device already? How much, and what type cigs do you smoke per day?
If the answer is no(or ~1 pack per day) then that little one you linked would likely be fine as a backup(spare) but the small size(400mAh) would almost certainly be challenging to go all day without having to recharge( which takes 2-3 hrs). The small unit is a nice unit but your current set of needs warrants something bigger(in my opinion) than 400mAh. If you can swing 2 of those you may be ok for the day having two of the small batteries on hand. Otherwise you should be looking for something above 900mAh, in order to have a better chance of only having to charge once per day.