FWIW, I bought a pair of of the
DJI lens inserts and put them in this afternoon.They were $29, came from Adorama via Amazon. I bought them at 4.5 diopters and found them to be quite precise, much more so than the cheap reading glasses I bought. Those worked pretty well, but I noticed some fall-off in focus at the edges and they did prevent me from seeing the entire screen, and one lens would ground just a little different from the other. The DJI inserts fit precisely over the
goggle eyepieces and are held in with a friction fit. They're $29 compared to $49 for the
Focus Fixers. Both eyes are very crisp and I can see the entire
goggle screen. They fit both the White and the RE
goggles. Definite winner and greatly enhances FPV flying.