Product review (5 stars): Inexpensive way to generate perfect balls of ice
These molds come in a pack of 2, each of which creates a perfect 2.5" ice ball. The ice balls have lower surface area than do square ice cubes, so they last longer and melt (and dilute your drink) less. They're also larger than your typical ice cube and I find that one per drink is more than adequate for most situations.

If you want the crystal-clear ice ball of your dreams, or of the videos you may have seen online of an ice ball press in action, you'll need to use distilled water. Anything else will result in clouded or cracked ice balls. Note that this is cosmetic only: the mold works fine with tap water and the ice balls will cool your drinks just the same.

Basically, you fill the bottom part of the mold to the fill line, then carefully press on the lid. I tend to be a bit sloppy, not to mention clumsy, so I do this in the sink. If you overfill, don't worry, as the lid has a hole in it and the excess spills over. Since some of that excess remains in the lid, I put my finger over the hole in the lid, then turn the mold upside down to drain off the excess. You put the mold in the freezer, wait 4-6 hours, and voil, a perfect ice ball.

To unpack the mold, remove it from the freezer and run some warm water on the top and sides. You pull the top off and when you turn the mold over you can either tap or squeeze and the ice ball will easily pop out. The product description says that they won't leak or tip and that is true but because of that hole in the lid (to allow for expansion as the water freezes), these have to be stored reasonably upright and level in your freezer.

These molds are larger than something that would make a single cube of ice. As a guess, 8 of them arranged in pairs side by side would be roughly equivalent to two ice trays stacked one on top of the other, so this isn't the most efficient use of your freezer space. If you're purchasing these, you're doing so because, hey, ice balls! Or because you're tired of diluted drinks. Or because it's a great conversation starter at parties. These aren't as cool to watch as a true ice ball press but they cost roughly one-twentieth the price so it's hard to complain.

The bottom line is that the molds did exactly what the product description said and I'm quite pleased with the results. I have no hesitation recommending these.

Disclaimer: the manufacturer provided a sample for review purposes with no restrictions on the review outcome. I have no personal or financial interest in the company or in anyone employed there.