We have 3,000, 4,000, 6,000 and 8,000 lb AMC cement blocks. Aquidneck Mooring Company blocks are made with rebar reinforced steel and solid 1 3/4" steel rod, completely welded throughout. Our blocks are 5' in diameter. We designed it round to prevent the bottom chain from getting tangled around the corners. The competition only sells square blocks. AMC blocks are made with high psi concrete so they are stronger. Our low profile design increases holding power compared to higher blocks which have a higher center of gravity and tend to flip over easier. We recess the 1 3/4" attachment eye inside of center of block and make double attachment eyes for long life. Aquidneck Mooring Company's rebar reinforced blocks are so good that we guarantee them for life if we annually maintain the mooring for you.