I've been storing this in a bag. I took it out of the bag for the photos. It's new and unused. (Photo) The distance from the inner thread to the inner thread is 5.5mm. Therefore, it seems to be the following: ↓ Skater Replacement Cap Unit Bottle Type One-Touch Capacity: 470 ml Compatible Bottles: Skater brand water bottles Compatible Model Numbers: SKDC4 Size: Diameter 6.5 x Height 6.4 cm --- I have other items for sale as well. Please let me know in the comments before purchasing if you'd like to buy a set. I will discount the total by 200 yen. ---