Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_21 (pick INTEGER, overall VARCHAR, position VARCHAR)
### Question:
Which Pick has an Overall larger than 308, and a Position of rb?
### Answer:
SELECT MAX(pick) FROM table_name_21 WHERE overall > 308 AND position = "rb"