After a few discussions, it seems not everyone knows about these

Mine consists of a foam "sock" that drops into the snorkel top and is held in place by the snorkel head.
The precleaner is oiled with the usual motorbike foam air filter oil ( requires very little ).
To say they are effective is a major understatement, after around 500km's of dusty driving my main filter is still like new.
The sock is simply washed in petrol, re-oiled and reused - the amount of dirt that it traps is mindblowing.
This pays for itself in no time, keeps the snorkel innards clean and can be washed out in the bush for multi day trips.
Can't recommend them too highly.
P.S. - air filter maintenance has been demonstrated to be "weakness" for some. You know who you are.
