Review on Leak-Proof Regular Mouth Ball Mason Jar Lids - Standard Size Caps for Mason Jars by Shane Yay

Unfortunately I did not use these lids on liquid jars before the return date. I tested three of the six in the pack on a pint can of Kerr. All three merged. I then tried the lids on a ball jar of the same size and they didn't leak. Testing with a second can of Ball resulted in some dripping at first, but it quickly stopped. Additional testing on a 1 liter can of bullets revealed occasional drips or a steady stream when the can was tipped. So if you buy them, test your jars before using these liquid lids. They lick more than they don't. So I don't recommend them for liquids. They are great for dry ingredients and I recommend them for storing dry ingredients. As stated in the product information, they should not be used for preservation.