The Avongard Crack Monitor consists of two overlapping acrylic plates. One plate is white with a black millimeter grid, while the other is transparent with red crosshairs centered over the grid.
Once the Crack Monitor is in position across a crack, the crosshairs shift vertically or horizontally on the grid if movement occurs,so that anyone can easily see and track crack movement .
This 496 page volume contains engineering tables, conversion charts, math formulas and much more, making it a must have for every engineer, manager, student or traveler.
