The Seco 40-Minute Heads-Up Grade Rod Level is a leveler for rods and prism poles. Fastening it to the pole or rod will assist you in determining that the pole is erected perfectly upright. This leveler comes with an added leveler on the side so that you can view it directly at eye level, thereby providing an element of safety that construction and surveying professionals need in traffic-congested or other potentially hazardous job sites. It also makes it simpler to level and connects to all sorts of rods and poles, in sizes from 1" to 1.25" in diameter.
A 40 min. vial is a less sensitive leveler than the 20 min. or 8 min. vials. This heads-up level would be best for projects that involve holding the pole by hand, thereby providing accuracy for an extended time. The other vials, though they are more accurate, won’t be able to provide the best service in areas with lots of vibrations, such as near roads or at construction sites. Therefore in those areas it would be best to use a 40 min. vial.