Nuk first choice latex teat size 1 medium the first choice teat has the special orthodontic nuk shape and an extra wide lip support to simulate breast feeding as closely as possible the nuk air system within the teat allows air to flow into the bottle though a vent as the baby sucks this ensures that no air is swallowed during feeding thus helping to prevent colic the nuk orthodontic shape and air system have both been approved by the british dental health foundation size 1 is su