The $69.96 Ultra-RX1 Kit from MidnightScience has no practical application. You know what--let me let you make that value judgment. Maybe you've been looking to find a receiver for listening to the ultrasonic sounds made by "insects, rodents, bats, and more."

Which is it? Am I nuts or is this cool? Nah--I don't want to know.

In the general scheme of the animal world we humans don't have particularly good hearing. Our frequency response is limited on the high end to around 20 kHz. Whatever's going on above that threshold is invisible to us. And, of course, that's where these (mostly) little critters are making noise. The Ultra-RX1 moves those high frequencies down to a range audible to us.

Part of the appeal is that this is a kit. In this day of large scale integration when multiple functions are programmed onto a single chip, you'll be pushing resistors, capacitors and diodes through a pre-drilled printed circuit board. The kit comes with detailed instructions including simple testing procedures at points along the way. That's to keep you from building past a mistake. A steady hand, small soldering iron, VOM (Volt Ohm Meter) and reasonable eyesight (or a magnifier) will get you through the project in a few hours.

Unfortunately, Google has not yet produced a Bat-to-English translation tool so you'll mostly be hearing clicks and sine waves with no explanation.