A tight absolute rated surface filter for low sediment applications.
Surface filters are best if you are filtering sediment of similar-sized particles. If all particles are 0.35 micron, a pleated 0.35-micron filter works best because it has more surface area than a depth filter.
An absolute 1 micron filter is one that traps 99.9 percent of the particles of 1 microns and larger. For most purposes, nominal filters are fine, but when very high grade water is required, an absolute-rated filter may be needed.