1/2". The top plate measures 18" x 4 3/4". The hardy hole is 1 1/4" square. The entire working surface, horn and plate, have no chips, gouges, repairs or breaks. The ring sounds like a church bell and the rebound is fantastic. I have had a few anvils that I've sold and this is the best one overall. I was just informed that this is a North Star anvil. According to Richard Postman's Anvils in America it likely dates to around 1930. Swedish anvils are considered to be of very high quality.
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