FEHB is an insurance program for federal civilian employees. It can cover many family members and covers certain benefits not covered by Original Medicare, including prescription drugs
Some options, such as the fee-for-service and the HMO, are limited by where you live. They also have limitations to enrolling and dis-enrolling.
If you are eligible, read through the FEHB Handbook carefully or call the Office of Personal Management at 1-888-767-6738.