I really like thse little sandwich bags by Natural Value. I don't know a lot about Kosher rules but these are Kosher certified so if that concerns you these are definitely worth buying. Not only that, according to my sister, they wash up several times and the zipper action works better than Ziploc. Now that's something to rave about! I find that Ziploc baggies smell "plasticky" so that's why I was very happy to find that these do not. I made up a batch of my "prairie girl gluten-free flour mixture" today and portioned it into my favorite little baggies. They're not meant for the freezer so I'll be putting the filled sandwich bags into a big Ziploc container (which I do like and use and re-use over and over again).