With Speedy Feeder when you get a real fast drinker, switch to a faster setting and let him go for it. When you have a weak or premature calf, needing careful feeding, switch to a slower setting and let it take milk as it can cope without drowning. The three speeds control the air inflow into the bottle, and thus the milk outflow. Reduce time wasted on speedsters and prevent drowning weaklings, all using the same bottle and teat.