CREATE TABLE table_2071644_2 (flange_thickness__mm_ VARCHAR, weight__kg_m_ VARCHAR)

What is the flange thickness when the weight is 19.9?
SELECT flange_thickness__mm_ FROM table_2071644_2 WHERE weight__kg_m_ = "19.9"
SELECT "flange_thickness__mm_" FROM "table_2071644_2" WHERE "19.9" = "weight__kg_m_"