Which Thickness has a Diameter of 21.9mm?
CREATE TABLE table_name_56 (thickness VARCHAR, diameter VARCHAR)
SELECT thickness FROM table_name_56 WHERE diameter = "21.9mm"
### Context: CREATE TABLE table_name_56 (thickness VARCHAR, diameter VARCHAR) ### Question: Which Thickness has a Diameter of 21.9mm? ### Answer: SELECT thickness FROM table_name_56 WHERE diameter = "21.9mm"