http://www.anvilfire.com/21centbs/Selecting-an-Anvil.phpFarriers anvils may look like any other anvil to the neophyte but they are a highly specialized type of anvil. Modern farriers anvils put a high proportion of the mass in the horn and often have just enough in the heel to balance the anvil. The base has negligible mass. Because the majority of modern farriers travel to the horse, most farrier's anvils are made in the portability range of 100 to 150 pounds (45 to 70kg). Modern farrier's anvils also have special features such as "clip horns" for forming toe clips and turning cams for ease of adjusting a shoe. Due to their very narrow waist most farrier's anvils are too springy for general forging work and should be avoided by non-farriers. All the currently available farriers anvils are cast steel or hardened ductile iron.
The horseshoe is forced between the turning cams, rotating eccentrics, making it easier to make the shoe narrower