Small Carpenter's Building Blocks, 40mm Base Unit, 3 Sets. 40x20mm x 64 pieces x 3 sets. These blocks are precisely made, ensuring no gaps, allowing you to build towers all the way to the ceiling. Since a large quantity is needed for block play, how about considering purchasing more? I bought these 12 years ago when my children were small, and we used them with a marble run and train tracks, and built towers. There are some minor scratches, but they are still in great condition and ready for play. Please leave a comment if you have any questions. Please note that I am not considering selling them individually.