i saw a stall at last month's MIAS offering Koji filters. Nung nakausap ko ung saleslady, reusable daw siya, washable, and no need to put any special chemical fluid to charge the filter.

has anyone used them? they're being sold by Herrick Filters(www.herrickfilter.com). afaik, they used to do OEM filters for a local car company here. not sure if Koji filters is their own product or dealer lang sila