CREATE TABLE table_46669 ("Grade" TEXT, "Description" TEXT, "Measurement" TEXT, "Function %" TEXT, "Estimated function %" FLOAT)

What is the measurement where the estimated function % is less than 20?
SELECT "Measurement" FROM table_46669 WHERE "Estimated function %" < '20'
SELECT "Measurement" FROM "table_46669" WHERE "Estimated function %" < '20'