When the visible light mode is used, the probe is placed touching the skin where the LEDs face the skin tissue. The probe is placed in one alignment, so the U-arm becomes parallel to the vein. On changing the probe's direction by 90 degrees, the position of the vein does not change. It appears as a dark streak with the diffused light illuminating the adjacent tissue in adults. In neonates, the same results are obtained with trans-illumination of the organ, and the vasculature is conspicuous from the opposite side of the organ. The output intensity of the LEDs can be varied and used for each wavelength separately or as a mixture, depending on the subject's skin color and fat content of the skin. The tourniquet enhances the vein appearance, and canceling the ambient light adds to the diffuse light component that has been multiply scattered by the visible light through the tissue. The green light gives a good contrast to superficial blood vessels that are not buried deep in the tissue. The red light provides a better visual enhancement for deeper veins and darker skin tones. The toggling between both the wavelengths allows the phlebotomist a sense of depth.