The size of a tennis ball, but smells much better. Pierce the lid and throw it in the corner of a room. Or take it out of the tub and place it into ventilation ducting.
Don't just mask odours, eradicate them at their source with OCD Cubes. Comprised of various essential oils these handy-sized pots can be placed almost anywhere you are getting unwanted smells for a quick and easy solution to the problem. The cubes can even be removed from the pot to place in different locations if you prefer.