Safety Guidelines For Hazardous Locations - National Instruments NI 9217 Operating Instructions Manual

Figure 1 shows the NI 9939 connector backshell.
Figure 1. NI 9939 Connector Backshell

Safety Guidelines for Hazardous Locations

The NI 9217 is suitable for use in Class I, Division 2, Groups A, B,
C, D, T4 hazardous locations; Class I, Zone 2, AEx nC IIC T4, and
Ex nC IIC T4 hazardous locations; and nonhazardous locations
NI 9217 Operating Instructions and Specifications 4 ni.com