Gro bags are one of the most popular and well known sleeping bags we use here in Australia and most parents either have used them or know someone who uses them. They are great for preventing moving babies getting stuck under blankets at night or not being covered at all and ending up waking as too cold. Though getting the sizing and TOG right can be a challenge with fluctuating day and night temperatures and even from the time you put your baby to bed till morning unless you are using regulated heating or cooling in your home the room can fluctuate greatly.
We always used the 1 TOG bag as we used heating to regulate the nursery over night though many use 2 bags, one for day sleeps and one for the colder nights. The guides are a great way to help you choose what is the best way to go. We have attached the guides here for easy reference should you need to refer to them.