1. Substitution Conclusion for 100DP3T1B9M1QEH A detailed comparison confirms that the E-Switch 100DP3T1B9M1QEH is functionally and mechanically identical to the original Grayhill 34ADP31B1M1QT switch in all major specifications. These include circuit configuration (DPDT On-Off-On), current rating (5A), DC voltage rating (28V), actuator style, mounting dimensions (1/4-40 threaded bushing, 6.35mm panel hole), and electrical life (40,000 cycles). This establishes a direct drop-in replacement. The only notable deviations are in the AC voltage rating (Grayhill: 125VAC; E-Switch: 120VAC) and a feature specific to the E-Switch part: epoxy-sealed terminals. The 5VAC rating difference is generally negligible in practical applications, especially within standard 120VAC mains environments, and does not compromise safety. The epoxy-sealed terminals on the E-Switch variant offer enhanced protection against moisture, dust, and vibration, thereby improving reliability in harsh conditions. In summary, the substitution is electrically and mechanically viable. The E-Switch part may provide superior environmental robustness. However, final validation is recommended if the original design strictly depends on the certified 125VAC rating or operates under extreme voltage conditions.