I've wasted more money than I intended on saving buying "cheap" ebay things for my motorcycle. I'm 5 for 5 on wasted ebay purchases. Honestly I'd be weary. Especially something electronic, and 90 dollars.
Theoretically, it should work like any made for motorcycle intercom/bluetooth systems.
Basically the main purpose being a "walkie talkie"/intercom between units (so you need at least 2 of them). Usually with a range of 900-1000 meters/yards or so (but honestly you won't get that much range unless you are in a flat, wide open salt plains or such).
They also connect to your phone via bluetooth so you can answer phone calls or play music like any other bluetooth headset.
Standard/lesser units can only do one thing at a time. But more expensive ones can do multiple (listen to music and use the intercom).
I like my Sena but eh... some things are spotty. Like range. Even just 200 feet/60 meters, thing starts to get static-y. No way in **** will this thing work at 900 meters in urban/city scapes. I have troubles talking to my wife 50 meters if line of sight is broken between buildings. Plus I seem to get a lot of interference to the point where I had to lower the volume a lot.
by the way, looked at the link. 90 bucks for 2. I see why its so tempting now. I think I bought my Sena slim pair for 260 when it was revzilla's black friday sales.