I use these whenever I'm travelling with nicer shoes.  I used to just put them in plastic bags but I like these better because I feel like the soft fabric is better for the shoes and doesn't hold humidity in.  I was surprised at how big of shoes I can fit nicely into these bags.  4 inch heels fit just fine but I don't think hiking boots would.  This is also one of the most cost-effective products out there since it comes with two pairs.  Highly recommended for frequent travelers.