Probably the best I've found is )I think) the Ofna stone filter. Stones are the best, but I haven't found a really good way to clean them. Other filters you'll find are 1 piece aluminum filters, and two piece aluminum filters. the 1 piece ones don't leak air, but the 2 piece ones allow you to clean the screen. I run the Stone filter in my Lightning buggy, and a 2 piece Dubro on my Savage, both work real well.