What is phase-correction in binoculars?

[retfed]

Doing to old internet research thing for under $200 10x42s I found a post that said...

"The difference between the Nikon Monarch and the Trailblazer is the phase-correction that you get on the Monarch, but not the Trailblazer. That makes the Monarch sharper, overall, but if you are pleased with the Trailblazer, I see no need to spend nearly twice as much on the Monarch to gain a touch more sharpness. For general wildlife work, either will work just fine."

[Dave in WV]

Phase correction is a set of coatings on the prism glass of roof prism binoculars that keeps light in correct color phases. These coatings are only needed on roof prism binoculars to enhance resolution, contrast, and color fidelity.
Poro prism binoculars don't need phase correction for the best resolution, contrast, and color fidelity and that's why they are less expensive to make.