To acquire the vested right, usually certain condition will be met; while in the contract when the main bodies contrast significantly, for the sake of the interest of the weak part, the acquisition of vested right should have to meet specific conditions.

• 既得解除权的取得，一般只需要满足一定条件；但在主体强弱势对比显著的合同中，为了保护弱势一方的利益，既得解除权的取得除需满足一般条件外，还须满足一定的特殊条件。