The test of love is an electronic circuit that detects the degree of love of a couple, so that the manufacturer of this device cuantotativa think that is a variable.
It is a circuit 10.4x7.8x2.5 centimeters, in which each of the participants held one end (marked with the symbol male or female), and the device itself determines the degree of connection between them represented on a scale red, yellow and green LEDs 1 to 10.
This is a mounting kit sold on this site for $ 17.