This adaptor connects large-diameter core bits (1-5/8" and up) with a 1 1/4" UNC female thread to smaller core drills and extensions with a 1/2" BSP female spindle. It increases equipment versatility, letting you tackle a wider range of jobs without multiple drill rigs. Precision-machined from high-strength steel, it handles the torque needed for large core bits while maintaining perfect alignment to minimize vibration, protect the drill motor, and deliver clean, accurate holes-an essential tool for professional core drilling.