The concept is simple. Thin lenses are placed along the seams where screens meet; they contain optical micro-structures that refract light, bending it inward to hide the bezels underneath.
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The kit’s optical obfuscation is designed to work at a specific angle. We selected 130° because it offered the best balance of comfort and immersion in internal testing. Proper fit and alignment are extremely important, so the lenses and associated mounting hardware are made for specific monitors.

Source: Bezel-Free Kit makes multi-monitor setups seamless | ROG – Republic of Gamers Global