Sometimes for working conditions you have to limit arms opening; as example to machining the roller support diameter with opened steady rest, or limit side arms obstruct, or to reduce steady rest opening and closing time.
This device usually allow to reduce the total trust cylinder stroke to 75%; the adjustement is manual and can be applyed on steady rests SLZ - SLZB - MG series.
This device doesn't limit the clamping range of the steady rest.