This is an IKEA Cabinet Light Sensor Mount designed to use with a non-contact IR sensor. This sensor opens when it detects the reflection of the signals (when it sees the door). The sensor can be purchased for around $10.
This simple bracket is suitable for IKEA SEKTION 802.65.398 cabinets as well as other SEKTION cabinets where the screw spacing is the same. The dimensions of the screws are Head: 7.3mm, Body: 6.2mm, Length: 12.9mm.