Manual Leveling Rotary Laser Levels
These are Laser Levels that the user must manually level using thumb-screws and bubble vials. While very good accuracy can be achieved, manual leveled lasers do not have the as great of accuracy as a self-leveling model (some manufacturers call it "Auto-Leveling" and some call it "Self-Leveling" which are two ways to say it). Also, the user has to be careful not to bump the tripod as this can cause inaccurate readings and you not know it, while a self-leveling laser level will continually auto-level itself. However, most auto-leveling laser levels do have a threshold or range that they can maintain auto-leveling themselves and that's about 5% up or down. Any bump or movement caused to a self-leveling laser level that's greater than about 5% will cause the laser to blink or shut off alerting the user its no longer to auto-level itself. Also, one needs to be aware that manually leveling a laser takes more time than a self-leveling laser, and time is money.