摘要：

A combination of square alloy rulers with precisely machined planes, each ruler unit having two 1.5v batteries and two bubble levels to level in all directions. A line generator is mounted in front of a laser diode module. This basic laser line ruler unit can produce an accurate laser level line or plumb line after it is calibrated. By adjusting the calibrating knob, the laser line ruler will produce a precise level line or plumb line when the level bubbles are centered. Putting a properly aligned level line unit and a properly aligned plumb line unit together will produce a cross line in front of the combination. Adding at least one more laser line ruler, that is combining three or more line units, will produce 90° lines, 45° lines, and 180° lines, as well as 270° lines up and down or on the right and left sides by simply adjusting the position of the relevant ruler. The housing of the ruler unit is machined with accurate planes and vertical angles. Therefore, the combination of several rulers can project accurate level lines, vertical lines, 45° lines, 90. degree. lines, etc. This simple, small, and unique ruler combination is affordable to the public and can be widely used in hardwood layout and cutting, carpet cutting, squaring the surfaces of any plane object, etc. in addition to its usage in construction.

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