Trimble Spectra Precision DG711 Sewer Pipe Laser System w Remote Fixed Curved Windows SEAMLESS SMART ROAMING: Uses your Type Size:Storage Door 18 1 2" SEAMLESS SMART ROAMING: Uses your existing network SSID name so you never get disconnected as you move around your home or office Metal chassis for rugged professional durability Once the grade is set it can also be locked avoiding errors by someone accidentally changing the grade The DG711 has a bright beam that can be easily spotted in the pipe and enhanced with the patented target that bends the beam upwards making it easy to see when looking down at the pipe reducing the need to bend down to see the beam when in the trench or standing above the trench