The bosch grl 300 hvg professional rotation laser offers outstanding visibility for indoor applications its green laser line provides up to four times better visibility than a red line and it is easy to set up in both the horizontal and vertical modes to the automatic self levelling of 8 plusmn 5deg there is a shock warning function which can be switched on and off that prevents levelling errors in the event of shocks or vibrations there are three modes for optimum visibility which are