This is a Tekmar 084 indoor sensor. It is new in the sealed box with the instruction sheet. This sensor can be used with many controls or thermostats that utilize a 10K ohm sensor. It can be laid flush to the wall which leaves just the rim ( maybe a 1/16 " ) off the wall or flush where the drywall mud or plaster wall finish covers it completely. So if you don't want to look at thermostats and they are compatible with a 10K remote sensor you locate the thermostats in maybe a closet and run a 18 gauge wire to this sensor. The sensor being hidden but in a primo sensing spot in the room. The 084 is a high quality sensor relabeled by many 2nd parties for their controls.