Question: What is the most common device model among female users between the ages 27 to 28?
SQL: SELECT T2.device_model FROM gender_age AS T1 INNER JOIN phone_brand_device_model2 AS T2 ON T1.device_id = T2.device_id WHERE T1.`group` = 'F27-28' AND T1.gender = 'F' ORDER BY T2.device_id DESC LIMIT 1