2.5" diameter approx.    Antique brass from Victorian times. These were the earliest types of brasses used to adorn horse tack. They will fit on a normal martingale for display, just the same as any other horse brass, but are ideally suited to being at the top or at the bottom. This particular style is possibly dating from the 1890's.  This one has a couple of rings of dots.

I am always happy to combine shipping on multiple purchases, which is the way to reduce the cost per item. (It is possible to get the shipping cost per brass down to as low as $2-$3 each for a larger order of 10-20 assorted brasses - depending on what items you choose - please ask for combined invoice.) Talk to me about your personal situation. I will always work with you to minimise your shipping costs.