Comfy Clothiers 10-pack Collar Extenders (Metal Button Extender) 10 high-quality metal shirt collar extenders per pack (10-pack) Get a 1/2-size of extra room, or daisy chain two together for a full size of extra comfort Discreet and disappears completely under any neck tie and stays in place Easy fit removable expanders - simply loop around your shirt's button, NO SEWING REQUIRED! 10mm (3/8-inch button diameter) metal collar extenders