The Seco Heads Up Rod Level gives the added sense of safety while doing routine surveys in traffic congested areas. There is no need to look down while traffic is flying by. The Heads Up Rod Level is also more comfortable and allows the user to keep his surveying instrument partner in sight for faster surveying. Due to the unique prism-istic design the bubble is direct reading and centered by moving exactly in the direction needed. The #5001-21 is suitable for use with track light, robotic instruments, or conventional leveling. 45-minute sensitivity.