If I'm honest, I didn't expect much from these.  Put one in my gym bag and four in my shoes.  They really do make a huge difference in odor.  The only part that ticks me off is when I forget to put these in my shoes at the end of the day, then when I get ready for work/gym and I get a big whiff of nasty odor.  From what I can tell, these don't REMOVE the odor like febreze, but they dang sure cover it up for a day.  Thought the price was a bit steep at first, but after a month of using them, they really are super effective and I'll be buying more.