Others say...

"Customer svc gave useless instructions + You don't actually need it "
[For "why you don't need it," jump to third paragraph.] First of all, this thing came without instructions of any kind. After a variety of unsuccessful attempts to get a vacuum in the jar, I finally called FoodSaver customer service. The agent said the sealer did not come with instructions because not many people have trouble using it. (They obviously don't read the Amazon reviews.) She instructed me to put my FoodSaver appliance on "vacuum and seal" rather than just vacuum, to have the jar ring screwed on while I was vacuuming and, if all else failed, to just leave the sealer on the jar (like a lid--without a vacuum). To her first suggestion, I asked if she understood how the FoodSaver appliance works, and had to explain that the "seal" setting only applies if you are using a bag or roll; I later discovered that the second instruction was just plain wrong (after days of frustration trying different jars, different lids, screwing the ring to different tightnesses, "seasoning" the lid with oil, etc.); and finally, if I can't get a vacuum in the jar, how on earth does it help to leave the sealer accessory sitting on top (and thus unusable with any other jar)?

Turning to Amazon reviewers for wisdom, I tried the two lid technique mentioned by one reviewer. (Put two lids on while vacuuming; the bottom one will form a seal.) Couldn't get that to work (but at this point, I was still following FoodSaver's incorrect instructions to use the ring under the jar sealer). So I tried the canister technique suggested by another reviewer. (Put the whole jar, lid and sealer into a Foodsaver canister and suck the air out.) Lo and behold, a vacuum formed in the jar!

Some Amazon reviewers have explained the principle of how this sealer works--the lid floats while the air is being pumped out, until the vacuum device is turned off and air rushes in to push the lid down onto the vacuumed jar. (Thank you!) From that information, I realized that I DIDN'T NEED THE JAR SEALER AT ALL. Sure enough, I screwed the ring snugly (but loose enough to let air flow) over the lid on the jar, put the whole thing into a FoodSaver canister, and vacuumed. When I let the air back in and opened the canister--viola--I had a vacuum sealed mason jar! This technique hasn't failed me yet. The down side, of course, is that you need an empty Foodsaver canister sitting around that is large enough to hold the mason jar. But if you don't want to bother with this troublesome jar sealer, you might try it. (Due to strain on the canisters, which are also reputed to fail, I wouldn't recommend doing this every day.)

Before returning the jar sealer to FoodSaver for a refund, I decided to give their customer service another chance to explain the proper sealing technique. This time, I got an agent who laughed at the idea of using the ring while sealing, and suggested that I try the two lid method again WITHOUT the ring. This actually worked--twice. On the next 20+ attempts (until I gave up), the jar sealer just laughed at me. So I give this device zero stars for lack of instructions, poor engineering, ignorant customer service and the fact that it is not really necessary, and one star because Amazon won't let me record zero stars.

"FoodSaver T03-0006-01 Regular Mouth Jar Sealer"
[[ASIN:B0000CFFS6 FoodSaver T03-0006-01 Regular Mouth Jar Sealer]
This is a very handy item. I saved on platic bags by using my Ball jars that I have on hand. I believe that we use too much plastic so I utilize glass where appropriate. I think glass is healthier and use jars that can be refrigerated or frozen. Just remember to allow about 1-2 inches head space or the jar will crack since liquids expand when freezing. I have 2 sizes one for regular jars the other for the wide mouth jars and they both work well. The plastic bags do an excellent job when they are needed for items that do not fit in the jars.

"FoodSaver T03-0006-01 Regular Mouth Jar Sealer "
Unfortunatly this product did not work. I called the company and they sent a replacement free of charge. That one did not work either. I have one for wide mouth jars that works beautifully, so think it may be that the one for small jars just does not work right.

"Works like a charm"
I have been looking and reading reviews for a while on this product, as well as the wide mouth one. I broke down and purchased both of them and began using them. I have sealed dried fruit, pasta, rice, chocolate chips and other things. If you do not use the products very frequently, you will want to check the seal every six months to make sure air is not getting into the jar. My children love helping me with it as well. It is fun for them to push down and then imagine the air being taken out.

I know a lot of people say they have trouble getting the lids to seal. A trick that was taught to me and has worked everytime is to place TWO lids and then seal. When the air has been removed, you can take off the top lid and the second one has sealed. It has worked EVERYTIME for me as well as for countless others that this advice was given to.

"Save on bags, No plastics leaching"
I do not like to store food in plastic containers or bags. I have had the wide mouth jar sealer for several years and use it often. The jars store uniformly. I was happy to see the jar sealer also came in the regular mouth size. I have sealed some cookies or crackers in a jar and forget them for months and they were fresh when I tried them. I seal loose tea, coffee, grains, flours, baking ingredients like raisins, nuts and chocolate chips. I keep yeast in a sealed jar for bread baking. I even cut bulk raw cheddar cheese into jar size pieces and sealed them a year ago. I still have two jars of cheese in the refridgerator and they are still great. I seal all leftovers too. I found 1/2 gallon canning jars at Ace Hardware and they sealed fine too.