Clamp is made of strong, thick walled 'cast iron'. The wooden "pen" is an easily interchangeable item that can easily be altered to suit each individual's desires. This anvil is of the same high quality as the one I found when I bought my first one in 1965. I gave it away a few years ago when I thought I wouldn't need it! In terms of "real money," this one was worth less than it was back then. Very good value for money! This is not a cheap "clothespin!" PS. This requires that the thickness of the tabletop not exceed 1ΒΌ"/30mm or 30mm. I quickly cut a notch 7mm deep and about ΒΎ/19mm wide in the bottom of my 38mm workshop table allowing the clamping screw to slide under the table top No problem Easily attaches to a jewelers/watchmaker's table.