There are 3 empty spaces for 3 additional suits. ii. I?ve even uploaded a video that shows how to do it. For consistent intense activity like hiking these would perform well, but MIGHT need replacing after a year or so. They are uber comfy, and fit my feet PERFECTLY (like, my heel is right at the back of slipper). Fit perfect, fast delivery, now I have a jillion of these stupid things for a crazy reasonable price. They also fit much better than the Sony and Apple. I ended up returning the whole thing. These shoes are so ugly. Long story short, I carry this in my gym bag and all my problems are solved.