Stylish Window curtain Clip/Metal Curtain Clip Rings 15 Pcs Black Internal Diameter: 3.15cm; External Diameter: 3.8cm. Stylish window curtain metal rings with clips and eyelets. The eyelets is used to affix the drapery hook on which drapes will be hung. These rings are great for full length curtains, as well as cafe curtains. They are helpful to withdraw the curtain easily and effortlessly.