I fitted one of these about 6 months back, you are not going to like what I have to say.
In stock form they are junk. If you don't need an air/oil seperator and have such low oil content in your breather then they will sit there and be okay.
If you do need oil seperation, they will not work, in fact combined with acceleration and the angles involved with off-road work they can feed your engine large gulps of oil. Potentially large enough to cause mechanical damage (hydraulic lock) and more than enough for the engine to run-away until it has sucked all the oil out of the intake.
In the short time I had mine fitted as instructed my engine consumed about 9 litres of it's own oil. It was so bad it ran on it's own oil at least 5 times, including when my wife was driving it alone and had no idea what was going on.
I seriously thought my engine needed rebuilt. I did rebuild my turbocharger, un-necessarily of course.
The problem is the vent arrangement.
Stock a provent puts oily air in the top, where it has to drain through the filter. The oil that drips out of the filter (blown by the air movement) is then spread around the lower chamber where a large proportion of it goes straight out the exit and into your intake.
Eh?
If you are offroad on an angle, the collection of oil from the filter can drop straight out and into the outlet to your intake without going down the drain.
I modified mine to work as they should have been originally. I gutted the pressure setting valve you see in the original outlet (lower port) and made this the inlet. I made some alumiminium spacers to block off the resulting holes in that cap.
I then connected the outlet to the top port.
The result now is oiley air enters the bottom and the oil has a path straight to the wall and down the drain. For air to get out the top port it has to first get centrifuged in the lower chamber and then pass through the filter element where it sheds the remainder of it's oil.
Working in this way (modified and contrary to manufacturers instructions) it works quite well as an air/oil seperator. My turbo and intake are the cleanest they have ever been and oil consumption has stopped. Luckily my engine survived ingesting this much oil.
But would I recommend people pay this much for a seperator and then modify it? Nope.
Instead get a large cheap breather can and use that. It will work just as well and not require modification.