SCHEMA:
CREATE TABLE table_name_43 (earpads VARCHAR, succeeded_by VARCHAR, construction VARCHAR, sensitivity__db_ VARCHAR)
USER:
What are the earpads of the headphone with a plastic construction, an unknown sensitivity, and was succeeded by sr325?

QUERY:
SELECT earpads FROM table_name_43 WHERE construction = "plastic" AND sensitivity__db_ = "unknown" AND succeeded_by = "sr325"