The slowest ones I could ever find were the Gerber Stage 1 Silicone. Dr. Brown's seemed to be a very fast flow on their slowest option. We accidently had one mixed in from the daycare with our nipple stash and I was horrified at how fast it was! The Gerber barely dribbled out and he used the stage 1 the entire time he was on a bottle (12 months.) They are just regular nipples that fit a standard bottle. We used the breastflow for awhile too, but the Gerber were even slower than those.