Guys, wanna ask how do I actually split 1 single Astro cable to 2 decoders, without pulling a new cable from the dish. Reason is my new place uses centralized dish and the cables are already concealed in the wall by the developer.

I found this device in an electrical shop and the guy said it will split the cable with no signal loss. Does anyone have any idea about this? Picture of the device as attached.

Thanks in advance...