Table schema:
CREATE TABLE table_name_43 (earpads VARCHAR, succeeded_by VARCHAR, construction VARCHAR, sensitivity__db_ VARCHAR)

Question: What are the earpads of the headphone with a plastic construction, an unknown sensitivity, and was succeeded by sr325?
SQL: SELECT earpads FROM table_name_43 WHERE construction = "plastic" AND sensitivity__db_ = "unknown" AND succeeded_by = "sr325"