MMV model single hand wheel manual monitors are constructed from stainless steel materials with 3” up to 4” water ways and up to 7000 l/min ﬂow rates. These models are equipped with a gearbox for vertical movement which is easy and precise to aim the monitor to the desired vertical aim. Specially designed worm and wheel gearbox geometry ensures self-position locking thanks to the engineered driving angle. This means the hand wheel shaft can drive the rotation wheel and move the monitor, but vice versa is not possible. The mechanism is therefore intrinsically safe and any out-of-balance forces in the monitor cannot move it oﬀ target.