CREATE TABLE table_6439 ("Location" TEXT, "Culture" TEXT, "# found" TEXT, "Ball diameter" TEXT, "Period" TEXT)

What's the Ball Diameter with the Location oof El Manati, and the Period of 1200 BCE?
SELECT "Ball diameter" FROM table_6439 WHERE "Location" = 'el manati' AND "Period" = '1200 bce'
SELECT "Ball diameter" FROM "table_6439" WHERE "Location" = 'el manati' AND "Period" = '1200 bce'