Retractable ring: This metal pen holder is equipped with adjustable spring rings. The diameter of each ring can be expanded from 7 mm to 17 mm, which can accommodate most sizes of pens or pencilsDurable material: These pen holders are made of metal and can be used for a long time; the adhesive design on the back brings convenience and is suitable for most occasionsWide range of applications: These pen holders can be clamped on whiteboards, refrigerators, wipe boards, bulletin boards, maps, calendars and other dry surfaces, and can even be a good help for storing shopping lists, pens, pencils, etc.Also are useful gifts to students, teachers, postmen, doctors, nurses.A nice helper for daily life and work:These pen holder clips help to hold small things, save users from looking for those things all the time.colour: blackMaterial: metalsize: diameter: 18mmPackage Contents: 16 x pen holderNote:Small items. please keep them from children under 3 years old.Only the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.