Narrow for newborn. U can also prepare a medium flow. Depends on how ur baby like it. Most will be ok w narrow or slow flow because that's more similar to the breast but some babies have big appetite so they like medium flow. My boy was always on medium flow since day 1
They have a narrow flow. if you intend to bottle feed and breastfeed at breast alternate. Always stick to narrow flow.
Mine was on narrow flow, then I changed to medium flow. Im using nuk latex bottle and teat.
Narrow. As small as possible