RS 683 Prospeed Xtreme Brake Fluid Prospeed is a revolutionary racing brake fluid. Not only does it boast an extremely high 583° F dry boiling point and a very high wet boiling point of 394°, but an innovative new manufacturing process actually makes this fluid more incompressible than other fluids! Meets DOT 4 specifications and is compatible with all DOT 3, DOT 4, and DOT 5.1 (non-silicone) fluids. 500ml (16.9 oz.) bottles. Dissolved air| Brake fluids are not a single element, but a mixture of several different ingredients. Conventional mixing traps tiny, dissolved bubbles of air inside the fluid. Fresh brake fluid typically contains a much as 5% dissolved air. Air is more compressible under pressure than fluid, so this leads to a soft pedal feel, even with fresh, brand-new fluid. CompressionFree™ Technology Prospeed’s patented manufacturing process minimizes the amount of air that gets into the fluid during manufacture. Instead of 5% air, RS683 contains less than 1% dissolved air! This results in a very incompressible fluid for the firmest pedal feel and most predictable braking you will ever experience.