These Copper Plated Dog Bells are constructed of high quality steel and are built to last. These bells emit clear tones that are great for long distances. They quickly attach to collars and are available in two sizes. The medium bell is 2" high and has an open bottom of 2" x 1 1/2". The large bell is 2 5/8" high and has an open bottom of 2 5/8" x 1 3/4". These bells are highly rust resistant.