Does it fit all bottles?

Fits most travel toiletries and cosmetics such as sunscreen, toothpaste, shampoo, conditioner, cleanser and more. (NOTE: Does not apply to pump caps!)

Is this sealed tight? Will it leak easily?

This is definitely a novelty, I put it over my plastic travel size bottles of conditioner, shampoo and oil and there was not a single leak. It's so flexible that it's still tight and as good as new after removing it with multiple uses.

Can I take it on the airplane?

Of course you can, for airplanes, trains, automobiles, cruise trips, etc. I've taken them through many cities and they've always worked perfectly, long or short distances, silicone covers are very easy to carry.

Is it disposable? Does it really work as well as described?

It works very well! Not only is it reusable, but it's also very easy to just wash it in water. It's exactly what I expected. You simply pull them off to cover the top of the container. Elastic sleeves are a great sealer to protect your products.

Will these work for standard size?

Yes, these are very flexible and fit round, oval, any shape and more. They are also flexible when using them and can stretch to fit all or most toiletries.