Had I known I could have purchased 5G for $40 (and it's on sale!!) I probably would have although it is still, IMO, completely unnecessary. How much purer can it possibly be than 4ppm? 2? 1ppm? I guarantee the filter in this unit will not get you even remotely close to this figure after one record wash. How much junk is embedded into the grooves after the drying cycle? There is a thin screen over the fan that cannot possibly filter the air very well. The more I think about it, the better I feel about that extra $37 in my pocket or record collection. The AD works great. Is it perfect? No.