Good laser levels are accurate withing 1/16 of an inch per 100 feet. This is ten times more accurate than a spirit level, which is only 1/2 inch per 100 feet. This 16 Lines Laser Level of precision is made possible through a laser diode that emits a concentrated beam across the area you need to level. Cross Line Laser Levels with variable speeds work well for interior work. A variable RPM allows the user to adjust the laser to the speed of best visibility. Slower rotations have a more visible beam. Faster rotations resemble a chalk line. You will want to set the rotation slow enough to where it is just fast enough to be considered a solid line on the wall, as this allows for the best mix of solid and brightness. If you need a solid dot reference set the laser at 0 RPM. The laser levels we just discussed are available with varying features. These features may include variable rotation speeds, beam scanning, grade capability, remote controls, rechargeable battery packs, AC chargers and more. Attachments may include a wall/ceiling mount laser platforms, detectors, and trivets for mounting a laser on its side to a tripod for interior work. We recommend you take the time to decide on which jobs or tasks you plan to accomplish while using an 8 Lines Laser Level. Possibly take the time to write these down on paper, then start your search. We recommend that you look over the varying comparison charts for David White, CST/Berger and Pacific Laser Systems Laser Levels as they can quickly point out which units have which features. We recommend you take the time to review the varying types of laser level specifications such as the range the laser will emit and accuracy specifications. Working with a construction laser level can save you time and labor while increasing your accuracy. Many setups allow a person to work alone when using a detector on a leveling rod instead of a two-person job with a regular (non-laser) level. A Laser Distance Meter sends a pulse of laser light to the target and measures the time it takes for the reflection to return. For distances up to 30m, the accuracy is É3mm. On-board processing allows the device to add, subtract, calculate areas and volumes and to triangulate. You can measure distances at a distance. Compared with a good, old-fashioned tape there is no contest. A Laser Distance Meter wins on every count: speed , accuracy, safety, versatility, convenience and functionality. Ultrasonic devices offer many of the same features but are less accurate.