First look, first Cup appearance. See gallbladder and bile surface finish is uniform, is there bruises and scratch defects; the second mouth welding is smooth, this one drink feel comfortable; three, poor quality plastic parts. Would affect the service life, will also affect the drinking water health; four internal seal is tight. Plug screw and Cup tie is appropriate. Screw spin out freely, whether leak. Fill a glass of water upside down four or five minutes or left a few times to verify leak.