Heat Seeker is designed for a precise heat detection placed on the caudosacral part of the back of cow. It is based on releasing of color from the cavity off the system after the pressure caused by mounting activity of the cow´s herd mates. The released color is a clear proof of an ongoing heat. The system is designed to resist the welfare brushings without giving any false positive reaction. Heat Seeker improves the heat detection and is able to uncover embryonic mortality. This prevents the farms from suffering from a huge economic loss.