Odour Neutraliser works by capturing and neutralising malodourous volatile compounds in the air. Thus, bad smells are eliminated rather than simply masked, although the block does emit a pleasant aroma of cherries. ON solid blocks are perfect for placing in internal ventilation systems to eliminate odours.  Simply remove the lid and place in the target area.  For a more powerful effect, remove the block from the tub, place it in the lid, and position it where you need it – this exposes a greater surface area of the block, and so volatiles can be captured more rapidly.