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_20297668_1 ( standard_yarn_weight_system VARCHAR, wraps_per_inch__wpi_ VARCHAR )

### Question ###
Name the standard yarn weight system for 9 wpi

### Accurate SQL ###

SELECT standard_yarn_weight_system FROM table_20297668_1 WHERE wraps_per_inch__wpi_ = "9 wpi"