Hagl&ouml;f 3-Thread Increment Borers (10"L x 0.169" (4.3mm) Dia.) Use to extract cores of wood from trees or freshly treated poles, piling, lumber, or timbers Teflon coating protects bit against rust and resin build-up and reduces friction 0.169 for general forestry use 0.200 for wood preserving testing 0.500 for large amounts of wood for qualitative analysis