These washi holders are absolutely amazing for compacting and organizing your washi tapes. You get the empty holder (no cores inside, the top comes off with firm pulling), a winder with an empty core, and 4 extra cores. The cores are 15mm wide, and you can fit at least 4 cores inside the holder once you've spooled your washi onto them. Word of warning: a standard roll of 15mm washi tape will fill 3-4 cores to the size that will still fit inside the holder. A good rule of thumb is don't wind your washi past the diameter of the winder if you want it to fit in the holder.