The phrase "flow teats" refers to the nipples on a baby bottle that determine the speed at which milk or formula comes out. It means how fast the liquid flows from the bottle when the baby is drinking. Full definition
Pack contains: 2 x 9oz Avent Natural baby bottles complete with slow flow teats (1 month +) with a hygienic snap - on lid. (littleangels.ie)
Of course he's also going to need bottles to feed the baby so you may decide to go for a sterilizer or set of faster flow teats for the baby as it gets older. (best-baby-gift-ideas.com)
Pack contains: 2 x 4 oz (125 ml) Avent Natural baby bottles complete with newborn flow teats (0 month +) with a hygienic snap - on lid (littleangels.ie)