The VHS series pressure relief valve provides a convenient means of isolating supplied pressure in a pneumatic system and exhausting downstream pressure for maintenance purposes.  The units can be locked in the exhaust position and can be an integral part of an energy isolation system.  Air flow direction is easily identified by handle orientation and labelling.  

VP5/717 series is a residual pressure relief 3 port valve with modular connection to SMC's AC series F.R.L unit.  It allows for space saving compared to non modular type.