Each link is hand forged individually out of American stainless steel alloy. Individual links are 1.75cm long and 1.2cm wide at the widest part. Measure your dog's neck where you wish the collar to fit. When you click 'Add to Cart' our handy chart will pop up and you can determine and select how many Add-On links you'll need. Each link is equal to a little more than 1/2" when added to the collar.