Looks very much like the one I picked up on Taobao for a fraction of that price (no idea what the extra board is supposed to do as it just outputs an on/off signal). The type number is almost the same even.
I tested it on a small plastic container and it works. Haven't used it beyond that. I think it's a capacitive sensor, it's got a small screw to adjust the sensitivity. Won't work on metal containers, only plastic or other non-conductive material.