SIZE: Diameter 18mm,20mm,25mm,30mm COLOR: Clear MATERIAL: Glass USAGE: Decoration for sofa/headboard or other DIY home creative decorations. REMIND: To protect and keep the good looking of the tacks, we suggest you to use rubber hammer for installation. When you receive and open the parcel box, please be carefully so as not to be scratched by the screws. Please put the item where the children cannot get it. This item should be used indoor and keep it away from the corrosive liquid.