We use a breathing sensor pad and this is perfect for keeping our very active baby over the sensor. It's also great when we don't use it, she spends too long standing up and crawling around the cot, and not getting to sleep. Love it when we travel too as we don't have to take our portacot with us when it's not convenient. Downsides: If I want to get her out of bed without waking her (dreamfeed or nappy change in middle of night) it's really noisy to separate the velcro and wakes her up straight away. It can also be a bit of a mission to get onto the mattress, and lining everything up perfectly. There's no real solution to this without limiting it's flexibility in fitting different mattress sizes so this is just laziness on my part!