I bought this to use with mason jars. It doesn't actually fit the jars but includes an adapter. The adapter includes a very thing silicone ring, which broke after 4 uses. The adapter will not hold liquid without the ring. I have tried to find out how to buy replacements with no success. Actual silicone rings from mason are too thick and will not allow the blender to work. Wasted purchase.To my way of thinking mason jar ready means you screw on a regular mouth mason jar and BOBS YER UNCLE. But this isn’t that, instead it’s an adaptor that only works without leaking if you muscle it on so it won’t come off, you then screw that adaptor on their regular blender base. Two points of failure instead of one!This method leaves you with a permanent glass jar that only works as good as the plastic one that shipped with regular Tribest blenders. So after years of wishing, in vain, that I could find the perfect solution that lets me blend and use multiple glass jars of which I have dozens, I GIVE UP. No one makes it and I suspect for good reason. The Mason threads and glass lip standard described in a 1857 patent are far too course for any modern manufacturer. The only solution is to either 1) say it has a mason jar that is really only labeled and branded and looks like a mason jar but is sized and threaded just like the manufacturer prefers OR 2) ship an adaptor. Either way, you can’t really use a cabinet full of Classico Pasta Sauce jars, which should fit and not leak.Now let we say this is YAGSB (yet another great smoothie blender) but is not for people like me who wish someone would simply make a blender that has a base that screws on the regular mason jar and then sets directly on the blender.I’m sadly afraid to say that this is a great blender - but that it isn’t natively compatible with the age old mason jar. Wish it was though.PLEASE READ THE BOTTOM EDIT AS I STARTED OUT THINKING IT WAS A GREAT PRODUCT...NOT ANYMORE! DO NOT WASTE YOUR MONEY!This blender is super in its use and I love it.Couple of things that are not so good:The downside is that the plastic tops are so fine in the rings that one of the broke/collapsed so that storage for one wasted already.The smallest glass jar arrived damaged. A piece of glass was broken on the outer srews and no one ever got back to me after reporting it with amazon. It is still usable but the cleaning is dangerous... too bad no one ever responded. Anyone know where to fill a complaint about it? Its nothing big but I just think the communication must be there, no matter what it says.Another thing, I got another mason jar and ..... the connection piece does not work on it, the screw is a little too big so I can't use it on this (larger) mason jar. Weird and I do not get why this is the case.Also I personally do not like that the glass ones are so narrow, it is hard to clean as my hand does not fit it. If you have small hands, it might not be a problem but I'm rather tall :)Apart from these I still love the blender and use it about 20 times a week and my partner started using it as well so I think we are getting some more containers. I would get it again, but not sure if I would go with glass again!_______________________________________________________________________________________________________________________________*** edit July 13, 2012 ***After 6 months of happy use my blade got a major leakage and a lot of liquid came out while I was blending...I discounted, cleaned it and let it dry for 2 days and tried it again with the dry grinder, the machine still works.I called Tribest and they ship me another assembly hooray! So awesome that Tribest has great customer service (I did buy on Amazon).I do use the glass only the little one for grinding occasional coffee fresh for guests or nuts/seeds which is working well. The larger glass onces we do not use (hard to clean as they are so narrow and the mug one has a weird internal whole in which we can't clean.Still love this blender and use it daily!_______________________________________________________________________________________________________________________________*** edit January 22, 2013 ***I would not buy this item again!! The same thing happened to my second assembly with much less use and its even more loose then the first one was. This time I never got a response after two emails to TRIBEST...wow. I guess it's such a common thing they can't even replace it anymore. Sad but true.My next purchase will NOT be from TRIBEST, I will change to a brand I have heard nothing but good from plus their many years of great costumer service can't be beat (7 years with option to but 3 more so 10yrs).In the end TRibest is way more expensive, super frustrating as food is running into the machine as I use it (and not just drops! picture it aaah) and it looks like the knifes will fall out any moment.What I like about this blender is the Mason jar attachment. I have a lot of Mason jars and I drink 2 protein shakes a day, so that's why I bought it and it works if it's just powder amd liquid. Add any kind of fruit and you will be drinking chunks. I've had a baby bullet, another multi baby blender/steamer/chopper, a Braun, a b&d, hamilton beech, oster and others over the years and they all are pretty consistent in texture. This is the only one that has chunks. And if I blend for longer periods, the liquid becomes warm. So because i have to keep another better blender in the cupboard, and because i pretty much only use it for my protein shakes, sans fruit, I'm giving it ⭐️⭐️⭐️.Very good blender. An adapter allows you to blend anything in a glass mason jar (and four different ones are included). I wanted a personal blender that has glass cups and this was the only one I could find. My previous one had plastic cup which eventually got etched from all the smoothie blending. This got me concerned about what else I was getting with my smoothie. Blending in the glass containers is acceptable, but it does not have the baffles that the plastic containers have so the mixing and blending is not as good and the smoothies can be a little lumpy. I am fine with this, but you should keep this in mind. It also comes with plastic containers if you want a smoother drink.The blender motor is strong and runs smoothly, much stronger than other personal blenders I have seen. There is an attachment for grinding nuts and grains so you know it has to be strong.I leave the blending unit at work. After dinner, I fill two of the mason jars with my smoothie ingredients to take to work the next day. I blend and drink my smoothie at work at about 10:00 am and 2:00 pm.I loved the concept and especially using glass jars because I don't trust plastic at all. However, the mason jar proved awkward to attach using the special attachment...it was hard to screw it tight enough to seal liquids and then hard to unscrew after blending. In the end the blender quit working entirely and I was so disappointed. Maybe I got a lemon because it wasn't very powerful from the start and would throb, stop and start. I sent it back and am going with a bullet...crappy plastic but it does the job reliably.i liked the fact that you can use glass jars with this thing, but unfortunately, it seems to leak from the lid closure area...there is something wrong with the rubber seal. ended up returning it and buying another Magic Bullet...and putting up with plastic.Works perfectly. Great to be able to blend in a mason jar! I use mine every morning to make butter coffee. Excellent—highly recommend.