Spectra Precision GL422N-4 Dual Grade Laser w/ HL450 Laserometer

Set Simultaneous Slopes in Two Planes — Built for Serious Grading Work

The Spectra Precision GL422N-4 is a professional dual-grade rotary laser designed for contractors who need to establish and control slope in two perpendicular axes at the same time. Whether you are grading a commercial parking lot, laying drainage slopes across a large pad, or fine-grading a sports field, the GL422N-4 eliminates the guesswork and repeated setups that slow down production. This kit includes the GL422N-4 laser and the HL450 laserometer detector, giving your crew everything needed to get on grade fast and stay there.

Product Overview & Jobsite Applications

The GL422N-4 uses a motorized, self-leveling platform capable of projecting a spinning red laser beam while simultaneously holding user-defined slopes on both the X and Y axes. The instrument covers a working radius up to 2,000 feet in diameter, making it well-suited for large commercial earthwork, civil grading, and site development projects. Remote-control operation lets operators adjust grade settings from grade stake to grade stake without walking back to the instrument, keeping productivity high on sprawling sites.

Key Specifications

• Grade Range: ±10% on both axes simultaneously
• Grade Resolution: 0.001 ft/ft (0.1%)
• Self-Leveling Range: ±5°
• Working Radius: Up to 1,000 ft (2,000 ft diameter)
• Laser Class: Class IIIa / 3R red beam
• Rotation Speed: 100, 300, 600 RPM selectable
• Accuracy: ±1.5 arc seconds (±1/16" at 100 ft)
• Detector Compatibility: HL450 (included), RC402N remote compatible
• Power: Rechargeable NiMH battery pack — up to 30 hours runtime
• IP Rating: IP66 dust and water resistant

What's in the Kit

• GL422N-4 Dual Grade Rotary Laser Instrument
• HL450 Digital Laserometer Detector with Rod Clamp
• NiMH Rechargeable Battery Pack
• AC Charger
• Carrying Case
• User Manual and Quick-Start Guide

Job Applications

Commercial Site Grading: Establish complex cross-slope and longitudinal-slope profiles simultaneously on commercial pads, eliminating multiple instrument setups and cutting machine time on large earthmoving operations.

Parking Lot Construction: Dial in precise positive drainage slopes on both axes to meet ADA and local storm drainage requirements, ensuring consistent sheet-flow performance across the finished surface.

Sports Field & Athletic Facility Grading: Maintain tight, uniform crown grades across football fields, soccer pitches, and multi-use turf facilities where surface tolerance directly affects drainage and playability.

Agricultural Land Leveling & Drainage: Control field-wide cut-and-fill operations with repeatable grade accuracy, reducing ponding, improving irrigation efficiency, and protecting yield across large acreage.

Compatible Accessories

• RC402N Wireless Remote Control for GL400 Series
• HL450 Replacement Detector / Spare Detector
• Spectra Precision Tripod — Heavy-Duty Elevating
• NiMH Rechargeable Battery Pack (Replacement)
• Machine Control Mast and Blade Sensor Cables

Related Guides

• How to Set Dual Grade with the GL422N-4 — Step-by-Step Guide
• GL400 Series Laser Comparison: GL422N vs GL412N vs GL422N-4
• Using a Rotary Laser for Parking Lot Grade Control
• Rotary Laser Detector Troubleshooting Tips for the HL450

Frequently Asked Questions

Can the GL422N-4 set independent slopes on both axes at the same time?

Yes. The GL422N-4 is specifically designed for simultaneous dual-axis grade control. You can program a different slope value on the X axis and the Y axis independently, and the instrument maintains both grades while rotating — no sequential setup or manual tilting required.

What is the maximum grade range on each axis?

Each axis supports a grade range of ±10%, which covers the vast majority of civil grading, site development, and drainage applications. Grade increments are adjustable in 0.001 ft/ft steps for fine resolution control.

Does the GL422N-4 work with machine control systems?

The GL422N-4 is compatible with aftermarket machine control receiver masts and blade sensors commonly used on motor graders and dozers. For full machine control integration, verify compatibility with your specific system manufacturer before purchasing.

Is the RC402N remote control included in this kit?

The RC402N remote control is not included in the GL422N-4 kit but is available separately. The remote lets operators change grade values and rotation speed from the machine cab or from grade stakes without returning to the instrument.