I'm using RX inserts in Sinister II's, they work good, I can see very well, easy to install/remove for cleaning, they'll scratch up the 509 lenses where they rub on the sides, not noticeable from the outside tho. Fogging isn't much of an issue if you have a no-fog mask or a good breathe box seal (anything will fog up if breathe/moisture get to them). No fogging when the airs moving, but if you stop sometimes you have to take them off to avoid fogging (not all the time). Same thing if ur breathing heavy or stuck.
FYI they are expensive, and i noticed my glasses fit very well in the sinisters, so if u dont wanna pony up the doh try that first. Also, can't fit the de-fog fan module in the goggles if u have an insert (I hear they don't work anyway). And RX doesn't make an insert for aviators, just sinisters.
