update (7/11/2012): 5 months now since I first used these bags. I'm done nursing and we started to use all the saved up milk. Out of the 150 bags I used in the past 5 months, I did have <5 bags leaked from the beginning. All were from the same batch/box. I think the brand has quality issue. However, I am experiencing bag leaking during defrosting. At first, I figure, maybe the leak bags are the few I might have dropped to the ground when shifting things around in the freezer. But I got one bag (5/8), newer milk that leaked again during defrosting and I know I have not drop any since April. My husband just told me now that he likes these bags, they feels more sturdy. Overall, would I continue using these bags? I think so because it is cheaper, holds more and the leaked bags could be my fault (since the leak were at the bottom and for sure they were not leaking at first). Oh, forgot to mention, the 5 bags leaked straight from the box were leaking at the top, at one end of the sealer, it just leaks. I try to reclose few times and milk just keeps coming out from one end. looks to me a quality issue.================I was Medela bag user for my first 2 kids and on my third kid, after reading another user's review, I decided to try these brand, because it is cheaper than Medela. For my needs, these bags are just as good, cheaper, and I love the bigger size.For the first time moms, here are my cons and pros and I will try to explain everything in detail. I have one Medela (backpack style) for all my kids, so I only know/use Medela stuffs. My sister-in-law let me borrow her freestyle on my third kid and I used it at work so I do not have to bring one pump back and forth everyday (and yes, you can use other's pump, just buy your own pumping kit, which you will need to buy few more anyhow to rotate while others are in wash).Con:1. if you pump into the bag, then these bags are not for you. Medela bags have strips to loop around the pump kits so u can pump directly into the bag. I pump into bottles, why, when you pumping, you want to sit comfortable (it is a good 15 to 30 min task), the bags will most likely rest on your lap/legs during pumping, and if you are not careful, it can spill if the bags are folded somehow when it is getting full (and you will, specially early morning time, when you are not fully awake). So, I pump into bottles, no worry about bottle folding and milk comes out. Since I use bottles, I do not need Medela's strips to pump directly into the bag. I simply after each pump, open these bags and pour the milk in. And one plus using bottle is u know exactly how much you pumped. Yes the bag has volume label, as you will see if you use any bags, the volume changes depending on the shape of the bag. It is a very loose/useless label2. I didn't like trashing the plastic strips. There is a strip you have to tear away per bag to open the bag. I do not like them becz my older kids can pick them up and play/chew with them, chocking hazard. I try to be careful and trash them, but we are talking about 20, 50, 100s of these strips after just first 2 months. Yes, you will have that much milk, if you are not lazy about pumping or nursing.Pro:1. the volume!! I definitely like holding almost 10 oz of milk in these bags. I am not sure if less bags save fridge room, since volume is the same, just less individual bags, but bigger/fatter and heavier bags. Fridge space will be your main issue later. We have 2 fridges and I am already running out of space. The milk are saved for later use, by then the baby is drinking at least 5oz, so one bag is plenty for one meal and some. The Medela holds about 5oz, so I remember my mom use to take 2 out just in case. Not a big deal, but one is somewhat less work than 2 bags and save money on bags.2. The opening shapes helps pouring the milk out. I am not usually the one that pours the milk out of the bag (my mom and my in-laws does that part, since they took care of my first 2 babies). But the few times that I did with medela, I pour the milk outside the bottle a lot. I guess it is a skill one has to acquire through practice. With these bags (when I over fill the bags, lol... I am a good producer), I had to take some out but I do not spill. I am more careful since it is a lot of milk (10oz) but the opening can be shaped nicely that just guides the milk into the waiting bottle. Medela bag, since the plastic is thinner, it takes few practice to hold the bag just right when pouring the milk out and I leave everything on the bag now so the extra little strip on Medela bag seems to help the pouring part also. The extra strip on Medela bag is for pumping into the bag. The plastic strip holds the paper strip that is looped around the pumping kit when pumping (confused? sorry, no pictures).Over all, To save money, these bags are just as good if not better. I never had leaking issues with any bags (unlike other reviews). These bags does smell, but so did Medela. The smell is plastic sterilized smell, you will smell a lot of that when you sterilize your plastic bottles. That is why I use only glass for my kids and glass heats and cools milk (a lot) faster than plastic. Evenflo makes nice 4oz, I personally do not think you need the 8oz bottle, because my 2 years old drinks 8oz, but she can't hold a 8oz glass bottle, it is heavy. So, we got 8oz plastic for her nightly snack. lol...Bottom line, everyone is different, everyone has their own style, preference, needs. First time mom, try both bags, you never know. I only decided to try these because I was using 2 or 3 Medela bags and it was getting expensive and after all the work/money, your kid might not drink pre-frozen milk!! Yap, my first one did not like the taste, so now, after first month, I start taking out frozen milk and gave to my 2nd and 3rd kid, so they get use to the taste and not as picky as the first one. Ya, first kid is always the learning kid.good luck!I really like these bags. The plastic is durable and much more stuff to pour milk in. I’ve used other bags and the popular Lansinoh bags are so flimsy compared to these.These are great with accuracy of ounces. Which is great so I don’t have to stress about having a bottle and my pumps to store milk in. I have bought there twice already and not looking for another brand to store my milk in.These are the best bag for breastmilk storage. They're thick and easy to close to ensure no leakage. I haven't had a single issue with leaking. Definitely worth the extra couple bucks!I love everything about these milk storage bags, from the labling area writability, the ziplocking and the thickness of the bags.Son grandes, y faciles de abrir y cerrar.Literally leaked every time I used them, don’t waste you money or milkI think these bags are one of my favorites. They are thick and durable. So far I have had no leaks or spills when using them. Sometimes they're a little hard to open once sealed but I prefer that vs some other bags that appear sealed and leak or bust open with a little pressure. I work to hard milking myself to have spills.He probado las Lansinoh y son muy buenas pero casi cuesta lo mismo comprar 50 de esa marca que 100 Dr Brown's, a su favor puedo decir que parecen más resistente y tiene excelente relación calidad-precio, lo que extraño de las Lansinoh es el doble cierre independiente, si bien las Dr Brown's También tienen doble cierre realmente no se siente independiente, el espacio es muy pequeño entre ambos y hay un margen entre el cierre y el borde de la bolsa al contrario con Lansinoh cuyos cierres tienen una buena separación y van de lado a lado de la bolsa, aún así por el ahorro seguiré comprando Dr Brown's.These are the best breast milk bags around. They're great value for money, and they hold the most amount of milk, which also means the least amount of wasted bag space. Great for exclusive pumpers. They are super easy to get all the air out of them for better and more efficient storage (without having to freeze them with air trapped in the bags). I'm an exclusive pumper, and a milk donor to BC Children's Hospital, and these have been amazing. Highly recommend them, and they're also great value. I'm not having to place an order every week for another box of bags.Fue una excelente adquisicion.. Anteriormente estuve usando bolsas avent, son buenas pero caras. En cuanto a precio no quise arriesgarme a comprar algo muy barato ya que no todos los comentarios eran buenos y con tanto trabajo que me cuesta sacarme la leche como para que se me eche a perder con bolsas desfectuosas, asi que compre estas bolsas Dr. Brown con un precio mucho mas accesible que las Avent. La primera impresion fue de desconfianza ya que el empaque no parecia como original, viene empaquetado en una caja blanca y dentro las bolsas en una bolsa ziploc. Sin embargo las comence a utilizar, son mas flexibles, mas faciles de manejar q las avent, el material se ve también de muy buena calidad. Yo las uso para llenarlas con 4-5 oz y son practicas para transportar ya que las lleno en mi trabajo, he utilizado hasta ahora unas 40 bolsas y no he tenido problema. Por todo lo anterior las seguire utilizando y recomendando.Es cierto que el empaque llega un poco roto por fuera, sin embargo por dentro viene sellada creo que el precio es mas bajo que en Liverpool, me confunden las medidas de la bolsa ya que no coincide con las del biberon al momento de vaciar la leche, en resumen son muy buenas bolsitas para guardar leche ademas de ahorrar espacio ya que las puedes congelar acostadas y se hace como una placa ligera que no necesita tanto espacio en el congeladorThese are well-built bags but the zipper is too finicky. It's not easy to close, I have to double check them all because it is so sturdy that it's hard to seal. I've lost 4 bags of milk because the zipper wasn't quite closed and they have leaked all over my freezer. The zipper placement also makes it difficult to pour milk into a narrow Dr. Browns bottle. I could get past it if I didn't lose 20 oz of milk but I haven't had any issues with the other 5 brands I've tried so these won't be purchased again.