So being the OCD kitchen girl that I am, I love it when I find a tool, etc. that not only has the form and function I want, but also looks very cool. So when I decided that I needed to open up some space in my spices/baking ingredients cabinet, the logical thing was to replace the pretty oil and vinegar bottles in my corner glass-door cabinet with things that I actually use. (Behind the bottles were/are extra glassware, etc., so that space was already functional, but what was at the front was totally decorative.)
So I got/saw the bright idea to put my various cocoas, baking chips, etc. in the tall straight mason jars I use for keeping my nuts/dried fruits vacuum sealed. But the metal jar lids/rings were not an option because that would be a total pain to handle, and the white plastic lids that you can get for regular or wide mouth jars are not airtight and are way too utilitarian looking for something that's visible (in my world, that is).
Long story short, there was almost nothing suitable online in the wide-mouth size, and then I came across iLids. They are the coolest thing ever for mason jars! They are really well-made and have a gasket and come in colors (including black, my personal favorite). They're not inexpensive, but I think are a reasonable price given how well-made they are.
An added bonus is that, from what I can tell, it's a small start-up kind of company where someone had a great idea and actually had the guts and determination to get it produced and bring it to the marketplace.
So FWIW, that's my cool kitchen gadget tip of the month
p.s. They're on Amazon but they have a website plus a promo code that saves 10%, which covered the cost of shipping in my case (compared to getting them Prime).