What piece of equipment is used to secure a line at both ends of course height?

The use of a line pin is essential in masonry for securing a line at both ends of the course height. By inserting these pins into the ground or a stable surface at either end of the designated course, masons can attach a taut line, which serves as a guide for aligning bricks or blocks accurately. This setup helps ensure consistent height and alignment throughout the masonry work, which is crucial for both structural integrity and aesthetic appearance.

In contrast, other options like a trowel, chalk line, and brick hammer serve different purposes. A trowel is primarily used for applying mortar and shaping the joints between bricks, while a chalk line is used to snap a straight line across surfaces, but it does not secure the line at both ends. A brick hammer is designed for cutting bricks and tapping them into place but does not provide any function related to securing lines. Thus, the line pin is the appropriate choice for establishing a secure reference line in masonry.