Pros: Very easy to set up. No need to buy/install IR "targets."
Cons: Remote to be converted must use AA or AAA batteries
The "flying saucer" simply receives UHF signals from the transmitter and emits them via its own infrared LED. Just place it near the device(s) to be controlled by the converted remote and plug it in. The flying saucer's base also contains a charger for the rechargeable battery.
The product comes with an extra rechargeable battery, which you can leave in the charger. That way when the one in your remote runs down, just switch it with the spare and you're back in business.
I've seen this product sold in both 418 MHz and 433 MHz versions, so if you or a neighbor already has a UHF remote, pick the frequency that won't interfere.