The Mason jars that are compatible with our Rumble Jar filters are among the most widely available versions you can find (and they're also very affordable!). Quart-size (32oz) Rumble JarsThe complete 32oz Rumble Jar brewing kits already come packaged with the compatible wide-mouth Mason jar. In case you're buying the standalone 32oz Rumble Jar filter or you need a replacement Mason jar, the key things to look for are WIDE MOUTH (i.e. not regular mouth) and STANDARD (i.e. not the more obscure ones with odd sizes or fancy shapes). Half-Gallon Rumble Jars (filter-only)Our half-gallon (64oz) Rumble Jar filters don't include a Mason jar. In addition to these jars being super expensive to ship individually, tons of folks have told us they already have one at home they can use. You can sometimes buy a case of them in a store for about the same cost as buying a single jar online and having it shipped to your door. Chalk up a win for brick-and-mortar! That's the reason we go strictly filter-only for the half-gallon size. The other really nice thing about the half-gallon size is that there is really just one version (the wide-mouth version), so you don't have to worry about the wide-mouth vs. regular-mouth distinction like you do with the quart-size jars. With half-gallon jars, you'll pretty much only find them in the compatible wide-mouth form (except for a rogue "Extra Wide Mouth" decorative jar that we're fairly confident you don't own and wouldn't be tempted to use for coffee anyway). Please note: we've recently heard reports that a new company called Pur has recently started making half-gallon Mason jars, and since their dimensions differ than all other standard half gallon jars on the market, those jars won't be compatible with our half gallon filter. As always, feel free to send us an email in case you have a question about a particular Mason jar model, and we'll be happy to steer you in the right direction.