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_2071644_2 ( flange_thickness__mm_ VARCHAR, weight__kg_m_ VARCHAR )

### Question ###
What is the flange thickness when the weight is 19.9?

### Accurate SQL ###

SELECT flange_thickness__mm_ FROM table_2071644_2 WHERE weight__kg_m_ = "19.9"