FS (Front Surface) means the reflective layer is on the front side, resulting in a very sharp image.
With Rear Surface (RS) mouth mirrors, the coating is on the back of the glass.
FS ULTRA: very sharp and very bright image. The mirror coating is acid-resistant but offers only a slight anti-stick effect.
FS Rhodium: very sharp image, but not as bright as FS ULTRA. The coating is acid-resistant and provides the highest anti-stick effect.
FS Chrome/Titanium: very sharp image, but less bright than FS Rhodium. The coating is acid-resistant; the anti-stick effect is lower than with FS Rhodium.
RS silver: Very bright mirror image due to the mirrored back surface. At certain angles of reflection, a reflection occurs on the glass surface that does not coincide with the actual reflection in the mirror. This results in a so-called double image, also known as a “ghost image.”