The question was: I know that longevity annuities are designed to provide lifetime income to elders but I'm not sure how they work. Can you explain? Also, how available they are?
The answer is: "A longevity annuity might be viewed as a hybrid of a deferred annuity and an immediate annuity.
"Like the former, it is purchased in advance of the annuity starting date–typically, well in advance. However, like an immediate annuity, it offers no accumulation benefit and may provide for no benefits at all unless and until the annuitant reaches a certain age.
"…Very few insurers currently offer longevity annuities, although several are considering adding it to their portfolios.