tmcase is right, they are used in laptop battery packs. That means they are very likely unprotected ICR lithium ion batteries, the most dangerous type to use in any e-cig, even regulated ones like the Vamo, Provari, etc. Please don't use these Hawki!
The safest batteries to get are IMR lithium ion (not protected) or hybrid li-ion like the Panasonic CGR18650CH tmcase mentioned or Panasonic NCR18650PF. The hybrids will give you longer run times between charging.
RTDVapor is a trusted source of batteries for many people.