Swissstop describe this as a ‘high-performance metallic-based release agent with a biologically degradable carrier fluid that reduces the formation of brake dust’. It's claimed to reduce or eliminate squeaking brakes.
They instruct you to clean the brake rotors and pads with disc brake cleaner – we would advise isopropyl alcohol is better – then spray a light coating of the brake silencer onto the pads.
After doing this braking noise disappeared, but so did about half our stopping power. Noise is the result of friction energy being dissipated, and it seems that this product simply reduces noise by reducing friction and therefore power.