Posted by a reviewer on Amazon

Prevents leaks from ball brand plastic lids and ball brand glass mason jars

Posted by a reviewer on Amazon

In shaking up jars of these drinks i would encounter leaks in spite of these silicone seals under the plastic caps

Posted by a reviewer on Amazon

I discovered the problem was not the seal but the fit of the plastic cap

Posted by a reviewer on Amazon

Some are apparently slightly misshapen and allow leaks

Posted by a reviewer on Amazon

I can shake daily but if i have to open the jar and then put the cap back on the oils leak

Posted by a reviewer on Amazon

Solution would be to wash top and seal before putting cap back on

Posted by a reviewer on Amazon

Perfect size for my application the wide mouth plastic ball jar lids that arent as leak proof as they tout

Posted by a reviewer on Amazon

These seals fit below the beginning thread of the plastic and being nonporous silicon they stay in placewithout coming off when you remove the jar lid