"Cot death" - many parents are afraid of this. This is rare phenomenon, and probabilty can be predicted. But it is good to have device that will be watching over our baby with us.
Move and breath monitors track muscles such as diaphragm. When some problems become device alarms a parents or babysitter. Theese monitors saved children's life many times. Fast reaction and first aid (parents should be educated) can be salutary.
Modern breath monitors are very sensitive and durable ane easy in use. They inform about batery status, so don't worry about suddenly disable.
It is worth to invest in baby safety.