Fallout: New Vegas implants

Talking to Dr. Usanagi reveals that she sells implants to augment your S.P.E.C.I.A.L. abilities, and two other implants, a sub-dermal implant that makes you more resistant to damage, and a implant that allows you to regenerate health. You can only apply a limited number of implants, the limit being determined by your endurance.

You get 1 implant for each point of BASE endurance. If you get an implant for Endurance, it will NOT allow you to get an extra implant. For example, if your starting endurance = 6, you can get 6 of the 9 possible implants. If you boost endurance to 7 with an implant, you still will only be able to get 6 implants.