homnas ceramic diffuser 100ml essential oil diffuser (bronze) homnas super quiet & lifetime warranty: adopted ultrasonic technology, the diffuser is extremely quiet(<35db, like spring breeze whispers in your ears) when working, providing a quiet and aromatic environment for sleeping and working. our ultrasonic diffuser comes with a 12-month return and a lifetime exchange(within 12 months, seller covers the return shipping fee ). try our product without any risk.