MMV model single hand wheel manual monitors are constructed with stainless steel AISI 304 & AISI 316 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 easily and precisely direct the flow to the desired vertical aim. An especially designed worm and wheel gearbox geometry ensures self-position locking thanks to the engineered driving angle. This means that the hand wheel shaft can drive the rotation wheel and move the monitor, but it is not possible on the other way round. The mechanism is therefore irreversibly safe and any out-of-balance forces in the monitor cannot move it off target.