gn 717 are a range of low cost indexing plungers which function well in small dimensions. However, their use should be limited to such applications where high precision indexing is not required. The maximum heat resistance of the nylon plastic hand knob is 110c or 230f. features threaded body: steel, zinc-plated, blue passivated plunger pin: stainless steel, european standard no. 1.4305 spring: stainless steel, european standard no. 1.4310 pull ring version: stainless steel, european standard no. 1.4310 pull knob version: matte black glass fiber reinforced nylon plastic, not removable lock nut: steel, zinc-plated