Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_25721_4 (release VARCHAR, _number_of_discs VARCHAR)

### Question ###
Which release had 6 DVDs?

### Accurate SQL ###

SELECT release FROM table_25721_4 WHERE _number_of_discs = 6