When a laser is to be set on a flat surface where the laser beam is not centered in the pipe, use the Spectra 1230 Heavy Duty Trivet Plate. Using this system, the elevation of the laser beam can be set by either measuring down from a grade offset hub outside the trench or up from the floor of the manhole to the beam.
This invert plate has a unit measure of inches while the 1237 uses the metric unit of measure. This plate is composed of one-piece cast aluminum support plates that provide automatic self-centering of the Laser in 10 inches (250 mm), 12 inches (300 mm) or 15 inches (400 mm) pipe diameters.
These invert plates are used along with the 1239 Universal Fixed Pole for setups on the manhole bottom, outside of the manhole or in pipes larger than 15 inches (400 mm) diameter.