Sonicare is our trusted brand for decade, but both Replacement Brush Heads broke (inside metal arm broke and no longer vibrate) in 1.5 month of usage. We used Replacement Brush Heads before and never had a broken head except for worn brush. These suppose to last at least 5 months. We thought something we did, but the second broke right after replacement. They do look flimsy. Don't think we'll order this product online again.