Our reed diffusers have a net weight of 6 oz and last 3-6 months. Your diffuser will include a box of 36 reeds. The number of reeds required to scent your space will depend on the size of the space and how strong you prefer the fragrance to be. Smaller spaces usually require 4-6 reeds, larger spaces can require up to 12. We recommend changing the reeds once a month as they get clogged with dust and get less porous over time.