I must say wow for this bottle comes with cap which really convinience for traveling only just for $1, in the other way other bottle kit with cap will goest around $13+ which are too expensive, and the nipple seems to extract all the dust particles to the nipple which cause our daughter to cought for the first two weeks after we finally found out those clear nipple we bought at toy r us are $4-6 for 3 nipples, they extract dust/particles. so we order a bunch of similac nipples which most hospital uses, combine with this bottle, we able to use the cap on top of the similac nipple, but couldn't with any other nipples with this bottle. 4oz bottle is a great size for storing breast pump milks. we also has the medela bottle kit, it has a nice clearly print of the oz # on the bottle but it's fading out within 1.5mon and the nipple isn't that good compare to the similac nipple. so I would highly recommend to get this bottle in combine with similac nipple will make the best combo.