Coloplast Filtrodor - Ostomy Bag Charcoal Filters have integrated deodorizing charcoal to help release the gas that builds up inside ostomy bags. The charcoal filter also works to protect against odors by neutralizing them as they pass through the filter. To use the Coloplast Filtrodor filter you will need to attach the filter to the ostomy bag that you are using. Next you will add perforations to allow gas to pass from the bag through the filter. The pin to accomplish this is included with the filters. By adding more perforations you are able to adjust the flow rate of gas. More perforations will allow more gas to pass. This product can be used on ostomy bags that do not come with a filter or if you would like to add them as an additional filter to filtered ostomy bags that will also work.