German full featured private health insurance.
If your income through a German employer is higher than a certain level, you are permitted to leave the Krankenkasse and join a Privatkasse. In the Krankenkasse scheme, you pay a fixed percentage of your income and so, young healthy single workers end up subsidising the old, the sick, the unemployed and those with large families.
This ability to opt out of the need to subsidise those other groups is the main appeal of the Privatkasse scheme. There is of course a drawback. Once you enter the Privatkasse, you are not allowed to go back into the Krankenkasse scheme. So, you have to be certain that you can fund your private cover for the rest of your life.
Rather than the pooled social fund structure of the Krankenkasse, the Privatekasse is an insurance scheme and so your premiums will increase as you age or as you aquire dependants etc.
When you are in employment, your employer must match your contribution to the Privatkasse scheme but, after retirement, you have to pay for the whole deal from your pension or other resources.
As with the Krankenkasse, you need to be an employee of a German company or a self employed person in order to join the Privatkasse scheme.