Operating temperature
The temperature range at which the device is guaranteed to work for a sufficiently long time without failures, breakdowns and exceeding the measurement error specified in the characteristics. Note that we are talking primarily about the temperature of the device case, and it depends not only on the ambient temperature — for example, a tool left in the sun can overheat even in fairly cool weather.
In general, you should pay attention to this parameter when you are looking for a model for working outdoors, in unheated rooms and other places with conditions that are significantly different from indoor ones; in the first case, it makes sense to also make sure that there is dust and water protection (see "Protection class"). On the other hand, even relatively simple and "myopic" levels / rangefinders usually tolerate both heat and cold quite well.
Vertical projections
The number of vertical projections issued by the laser level during operation.
Most modern levels are designed for a strictly defined position when working; accordingly, the
projection is called vertical, carried out from top to bottom relative to the standard position of the device. If there are several such planes, the level can be used for two or even three walls at once — this is useful, for example, for the simultaneous work of several people. At the same time, there are portable devices that can be used in different positions; for them, the main working plane is called vertical, although during operation it can be located both horizontally and at an angle, depending on specific tasks. Also note that the vertical projection can also give a horizontal line — for example, when installing a level on the floor.
Note that the number of projections is calculated not by geometric planes, but by individual laser elements, each of which is responsible for its own “work area”. For example, if the level has two vertical elements located at opposite ends and directed in different directions, they are considered as two projections even if these projections lie in the same plane.
Point projections
The number of individual points projected by the laser tool — rangefinder or level, see "Type" — when working. In the first case, one
point projection is standardly provided — more is simply not required to measure distances. In levels, there can be several points, and some models do not have planar projections at all and work only with points. This format may not be as convenient as displaying lines; at the same time, with the same laser power, dot marks shine brighter and are more visible, especially at long distances. In addition, there are certain types of work for which point projection is considered optimal — for example, laying sewers, determining the locations for two holes in opposite walls, etc.
Zenith
Zenith in this case is called a point projection directed vertically upwards.
By itself, such a projection can be useful, for example, if you need to make holes in several floors, located strictly one above the other. It is enough to point the "anti-aircraft" laser at the hole located directly above it — and the mark from the beam that passed through this hole will indicate the point for the hole on the next floor. And if the device also has the nadir function (see below), then the combination of these functions will be very convenient for marking the floor and ceiling at the same time — for racks, partitions, etc.: marks from the zenith and nadir are located strictly one above the other.
