These are the insect pins that came with the soundproof panels for attaching them. I counted them, and there are 100 pins in one bag. Length: Approximately 2.6 cm Thickness: Approximately 1 mm in diameter (the head is approximately 2 mm in diameter) *These were included as accessories with the product in images 5 and 6. I didn't need them because I attached the panels with glue and double-sided tape. *I have a total of 10 bags, so you can purchase up to 1000 pins (in increments of 100) for an additional 100 yen per 100 pins. Please let me know in the comments section before purchasing if you need them. *It is also possible to purchase from 300 yen per bag. Please let me know in the comments section.