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_name_50 ( lap_length VARCHAR, category VARCHAR )

### Question ###
What is the Lap Length of the race with a Grand Prix Fia Category?

### Accurate SQL ###

SELECT lap_length FROM table_name_50 WHERE category = "grand prix fia"