Here are some possibilties:
http://www.speco.com.au/accair.html#weber
http://www.speco.com.au/accair.html#stack
http://www.piercemanifolds.com/airfilters.htm
Ian
http://www.speco.com.au/accair.html#weber
http://www.speco.com.au/accair.html#stack
http://www.piercemanifolds.com/airfilters.htm
Ian