Medicare Supplement policies are designed to cover expenses not covered (or only partially covered) by the "original Medicare" (Parts A & B) fee-for-service benefits. They are only available to individuals enrolled in Medicare Parts A & B. Medigap plans may be purchased on a guaranteed issue basis (no health questions asked) during a six-month open enrollment period when an individual first becomes eligible for Medicare.[128] The benefits offered by Medigap plans are standardized.