BetterVue (BetterVue is made by Phifer) is a type of screen that is mostly used for window screens. It is very nice to see-through, sort-of like there is nothing there. The strands are thinner so you can see through the screen easier. There is a similar type of screen made by a different company, it is called Clear-View.
Some companies that build screen enclosures did put BetterVue in the total screen enclosure (for a few years). The reason why this screen is not used any longer for screen enclosures is that it tares easily, slips out of the track easier as well as other problems. It also requires a different size of spline (rubber that holds the screen in the track). And most people who repair screens do not have the right size spline, and furthermore, did not even know that a different size spline was needed so they put in a spline that was to small. And the screen came out even easier and many more problems. Most of the enclosures where BetterVue was installed are in southern Florida (as far as we know).
The manufacture stopped making that screen for screen enclosures because of all the problems. BetterVue is still made for window screens.
If you have a screen enclosure that was screened with BetterVue you will eventually need to change to a different type of screen since BetterVue is no longer manufactured. You could call the builder of the enclosure and see if they still have some Bettervue and will repair it for you. They may charge you a lot more because it is no longer available. (It was the same price as regular screen (18 x 14) when it was available).
Regular screen(18 x14) is a darker screen so it may look like patchwork. 20 x 20 screen (smaller size holes) is darker yet. Gray screen could be an option but it sometimes has a shadow-like effect. There is not really any perfect solution. Maybe, you could convince the builder who built your enclosure to give you a really good deal to totally rescreen your enclosure with some type of screen that is going to be around for a long time (and has been tried and proven) for a screen enclosure.