When a tip is missing from the catalog, photos beat long descriptions. Send: (1) the full pen from the side, (2) the empty cartridge bay, (3) the tip or blister pack showing printed text, and (4) a close-up of the connector end.
Hold the camera steady and avoid heavy filters. Include any model stamp on the pen body or battery cover. If you have an empty blister, photograph the printed label as well — it often names the series even when the tip itself is unmarked.
Add the approximate quantity you expect to reorder. That helps us judge whether to quote a one-off source or a repeatable supply path.