none, rockers give parents a false sense of security for their babies and often leave them unattended causing accidents... https://www.cbsnews.com/news/infant-sleepers-rockers-babies-deaths-fisher-price-kids2/
https://babyology.com.au/health/safety/heres-why-those-helpful-baby-rockers-swings-and-sleepers-are-best-avoided/
https://www.todayonline.com/daily-focus/health/safe-sleep-babies?singlepage=true