This is a refill with a 0.5mm ballpoint diameter, providing a smooth writing experience. I accidentally bought the wrong size, so it's new and unused. - Ballpoint diameter: 0.5mm - Model name: SXR-5P - Compatible products: SXN-150-05 and others - Quantity: 5 refills To keep shipping costs down, I plan to send it directly in an envelope via regular mail. If you prefer anonymous shipping or more secure packaging, I will adjust the price to include the extra shipping cost, so please let me know before purchasing.