Collar stays (sometimes known as collar bones or tabs and in the UK, collar stiffeners) are shirt accessories.
Collar stays are smooth, rigid strips of metal (such as brass, stainless steel, or sterling silver), horn, mother of pearl, or plastic, rounded at one end and pointed at the other, inserted into specially made pockets on the underside of a man's shirt collar to stabilize the collar’s points.
The stays ensure that the collar lies flat against the collarbone, looking crisp remaining in the correct place.
Collar stays can be found in haberdashers, fabric- and sewing-supply stores and men’s clothing stores.
Collar stays should be removed from shirts before dry cleaning or pressing as the cleaner may forget to do this themselves. Shirts that are press ironed with the collar stays are vulnerable to damage.
Some shirts have stays which are sewn into the collar and aren't removabla