| Engineering Parameter | Pointer / Vibration Type (Analog) | Digital / LED Microprocessor Type |
| Operating Principle | Resonant Reed / Moving Coil Indicator | Microcontroller-Based True RMS Digital Sampling |
| Standard Dial Footprint | 52 mm ($2^{\prime\prime}$), 72 mm, 96 mm square | 52 mm ($2^{\prime\prime}$) round or DIN-rail square mount |
| Measurement Scale Range | 45 Hz to 55 Hz (or 55 Hz to 65 Hz) | 10.0 Hz to 99.9 Hz (Extended wide-band) |
| Sensing Sampling Voltage | AC 110V / 220V / 380V / 440V | AC 50V to 500V (Auto-sensing wide-range) |
| Power Consumption | $\le 3\text{ VA}$ typical nominal | $\le 1\text{ VA}$ energy efficient |
| Measurement Accuracy Class | Class 1.5 to Class 2.5 | Class 0.5 ($\pm 0.1\text{ Hz}$ ultra-precise precision) |
| Signal Source Input | Direct parallel connection to $AC$ Line | Direct parallel connection to $AC$ Line |
| Display Illumination | Optional internal filament bulb slot | Self-illuminated Segment LED or Backlit LCD |
| Ingress Protection Rating | IP42 to IP52 standard enclosure | IP65 front-bezel water and dust proof |
| Case Shell Configuration | Stamped Steel or Flame-Retardant ABS | Toughened Polycarbonate / Fire-resistant ABS |