Touch-Free Tank Toilet Flushing System Auto Flush Touch-Free Tank Toilet Flushing System Auto Flush  Item number:  QBO-I 1，Environment study time range: 1 minute 2, during the environment study,there shouldn’t have any thing in front of sensor within 130cm 3, the longest distantance is 90 cm 4, default setting Small flush(half flush): 4 seconds 5,default setting Big …