An impairment (exclusion) rider attached to a health insurance policy:

解析

An impairment rider (also called an exclusion rider) allows the insurer to issue a policy while excluding a particular existing condition or body part from coverage, so the applicant can be insured for everything else. It does not add coverage, lower the deductible, or increase benefits, its effect is to remove coverage for the named impairment. This rider lets an insurer cover an otherwise higher-risk applicant by carving out the specific problem.