Musk is widely used in this format in the arab and asian world.
It comes in small block tablets. If you leave it in your clothes drawers, its fragrance bursts out when you open the drawers and is gently imparted onto the surrounding clothes. If done with care, as the consistency of solid musk is a little crumbly when cut, the block may be cut in half or more, to make it go further.
A nice, simple and traditional item, yet very effective.
After a few weeks, the fragrance fades in which case, all you need to do is rub the surface layer a bit until fresh scent is released