Found Something Strange Under My Steering Wheel

[Chambers]

Hi all, my spedo isnt working and is squealing like crazy so I resumed to remove the panel below the steering wheel to check on the cables' condition and while pulling the panel out a small black box that has wires, a antena, and a plug fell out. I have no idea what this could be, upon taking the top cover off I discovered the thick black "wire" shooting out the back was a antena, and the two white and gray wires are running from two places inside of the box, I don't think thats how it came. In one of the pics you can see a adjustable screw, around it are the following words "TOPS TAIWAN," and there is a sticker on the bottom that says the following

"Model : AC-21
RF SEN : -21dBm
FREQ : 315MHZ."

Now this box wasnt connected when I was tugging on the panel, atleast I think it wasn't connected because it just fell out, thats the strange part, as you can see in the other pic the boxs' plug is wired directly to the wiring harness, I'm not worried to much because the car is running fine I would just like to know what it is, Thanks.