Polymer pressure is sensed by a metal diaphragm, mounted flush with the inside surface of the extruder barrel with pressure indicated on the readout gauge. The sealed diaphragm design eliminates the need for grease and prevents melt contamination and gauge plugging. On the rigid snout version the mechanical gauge can be rotated 300° for unobstructed viewing.

The PG4 Series includes models PG441R, PG442R, PG443R, TPG441R, TPG442R, and TPG443R.