Spectra Precision® GL622N Grade Laser — Easy-To-Use, Full Featured Automatic Grade Lasers. The GL622N Dual Grade Laser is rugged, automatic self-levelling laser with grade capability from -25% to + 25% and can be used for a wide variety of grade, excavating and alignment applications by general and speciality contracto Spectra GL622N - LASER W RC602N REMOTE, HL760 RECEIVER