iiyama says
What is the difference between the VisionMaster and VisionMaster Pro series?
Shadow Mask(=Flat square tube (FST))
CRTs have a plate which sits behind the glass between the phosphor and the electron beams.Holes in the plate are precisely aligned so that only the appropriate beam is allowed to hit the red, green or blue phosphor. A Shadow Mask absorbs the electrons' energy, which is converted to heat.
The distance between two holes in the shadow mask masking two adjacent dots of the same color is called dot pitch.
Shadow Flat Mask (Flat surface +Shadow mask technologies)
There are benefits to both technologies.
There is no visible 2 horizontal lines.
TrueFlat(based on Aperture Grille Technology)
TrueFlat is iiyama's brand name for its flat-faced monitor. Shadow Mask (FST) is an industry standard term used since 1997 indicating minimal curvature (but still a curvature) of the monitor tube. FST is not flat-faced like an TrueFlat. There are benefits to both technologies at this time. Flat-faced monitors from all manufacturers have some advantages & drawbacks. On the plus side, they have much less glare than the FST & images have a flatter, more realistic appearance. However, most flat-faced models employ a double layer glass surface that reduces brightness (and sometimes contrast) and can have warping at the corners. As technology advances, these problems become less apparent with every new product revision. FST monitors have a slight curve to their image, but may have significantly better brightness (and sometimes better contrast) with a price that is more accessible for most consumers.