press and hold for on off and tap button to change modes [SEP] at first i thought it did not work but it works like my bike flasher not like other flossers press on button for seconds to turn on off and tap the button to cycle through the modes it remembers the mode it was in when turned off too like my bike flasher does not hold a lot of water but very easy to refill cannot comment on battery life since i just got it perfect for travel since the nozzle fits inside and it collapses to inches takes very little space on bathroom sink my gums have started to receed and dentist suggested the oral irrigator to clean out food debris like this model a lot and i have used several just remember to hold the button down seconds to turn on