The kind that you put on the end of the vent hose, so that you don’t have to put it out the window, or pipe, and it condenses and collects the water.
Our condenser dryer died, and it is less expensive to buy a normal one, and I saw the option of using those boxes, but I have a feeling they don’t work.
Like this for instance
http://cgi.ebay.co.uk/TUMBLE-DRYER-CONDENSER-VENT-KIT-Made-buy-Whirlpool_W0QQitemZ130137393696QQihZ003QQcategoryZ20714QQrdZ1QQcmdZViewItem
Shannon