Rotary level Bosch GRL 400 H Professional

The Bosch GRL 400 H Professional Rotary Level provides reliable horizontal reference for outdoor and indoor site work with a maximum working range of 400 m and levelling accuracy of ±0.08 mm/m. Designed for straightforward operation, the instrument features Electronic Self Levelling within a ±5° range, an intuitive single-button interface and a removable battery tray for easy replacement. Built to withstand demanding conditions, the unit has IP56 dust and water protection and compact dimensions of 180 x 190 x 170 mm, making it practical to carry and position for a variety of levelling tasks.

Advantages

The GRL 400 H Professional combines long-range performance with simple operation: a one-button keypad enables quick start-up while the self-levelling system reduces setup time and human error. An accuracy rating equivalent to ±2.4 mm at 30 m ensures precise measurements for grading and construction lines. An ADS shock warning alerts the operator if the instrument is disturbed during use. The durable housing with IP56 protection and a NiMH battery that delivers up to 30 hours of run time support extended outdoor work without frequent interruptions.

Suitable for

• Site levelling and grade control on construction and civil engineering projects
• Excavation depth checks and cut-and-fill determination
• Setting foundations, concrete form levelling and slab works
• Landscaping, drainage planning and large-area alignment
• Survey tasks where a robust long-range rotating laser is required

Key specifications

• Maximum range: 400 m (rotary beam)
• Levelling accuracy: ±0.08 mm/m (±2.4 mm at 30 m equivalent)
• Self-levelling range: ±5°
• Protection class: IP56 (dust and water resistant)
• Battery type and runtime: NiMH battery, up to 30 hours operation
• Shock warning system: ADS electronic disturbance detection
• Dimensions: 180 x 190 x 170 mm

How to use

Set the rotary level on a stable tripod or mounting point and switch the unit on with the single-button control; the Electronic Self Levelling will automatically bring the instrument to horizontal within the ±5° range. Select the appropriate rotation speed and receiver settings for the working range and use a compatible laser receiver to detect the rotating beam at long distances. Monitor the ADS shock warning indicator during operation to ensure the device has not been moved; if the warning appears, re-establish the instrument position and re-run self-levelling before continuing measurements.

Usage recommendations

For best results, use the GRL 400 H with a purpose-designed rotating laser receiver suited to the planned range, mount the unit on a calibrated tripod, and verify level periodically during long shifts or after impacts. Store and charge NiMH batteries according to manufacturer guidance and protect the instrument from prolonged submersion despite its IP56 rating. When performing precision tasks, allow the instrument to stabilise after repositioning and confirm readings at known reference points.