Medigap / Medicare Supplement:

Medigap (or Medicare Supplement) is extra health insurance that you buy from a private company to pay health care costs not covered by Original Medicare, such as co-payments, deductibles, and health care if you travel outside the U.S. Medigap policies don't cover long-term care, dental care, vision care, hearing aids, eyeglasses, and private-duty nursing. Most plans do not cover prescription drugs.

Because Medigap plans reduce or completely eliminate copays and deductables, their monthly premium is generally higher than a Medicare Advantage plan.