These clever aids are a cost-effective solution for marking the opposite drilling positions for wooden dowel joints. The set contains four centre points made of strong steel. They have a shaft which you insert in the drilled dowel holes in the first part of your workpiece, while the other end has a protruding metal mandrel – this lets you mark the correct drilling positions on the complementary workpiece. You do this by pushing the parts close together and aligning them correctly. When you press the boards together, the metal pins of the centre points press into the wood of the opposite wood board and mark the correct drilling position for the matching dowel hole.