RL-H5A is the Next Generation Self-Leveling Construction Laser; With great distance and high-accuracy; Long-range operation (800 m); Smart long-range receiver; Simple, intuitive manual slope capability; ±10 Arc second horizontal accuracy; Laser product 2.4mW and class IIIa. Warning: This product can expose you to chemicals which is [are] known to the State of California to cause cancer and birth defects or other reproductive harm.