Air fresheners are made with premium aroma beads and high quality fragrance oils. The strength of fragrance will vary with each scent, some are strong as others are light. Most will last 30+ days. You may get used to the smell and go "nose blind" to it, but others can still smell it. Freshies come packaged in appropriate bags to hold scent as well as twine to hang from desired location. We recommend rear view mirror, locker, closet or other small area. Please refrain from placing on dash or other surfaces as oils used could possibly stain.