| Specifications | 1253 | 1251 | 1252 |
| IEC 60942 Class | Class 0 | Class 1 | Class 2 |
| Complies with ANSI S140 | Yes | Yes | Yes |
| SPL re 20 µPa | 124.0 ± 0.2 dB | 114.0 ± 0.2 dB | 114.0 ± 0.4 dB |
| Frequency | 250 Hz ± 0.2 % | 1000 Hz ± 0.2 % | 1000 Hz ± 0.2 % |
| Distortion | < 1% | < 1% | < 1% |
| Sensitivity to load volume | -0.00002 dB/mm3 | +0.0003 dB/mm3 | +0.0003 dB/mm3 |
| Typical change in SPL per year | < 0.01 dB | < 0.02 dB | < 0.02 dB |
| Time for level to stabilize | < 2 sec. | < 2 sec. | < 2 sec. |
| Microphone size * | 1" 1/2" 1/4" | 1" 1/2" 1/4" | 1/2" 1/4" |
| Temperature range | -10 °C to +50 °C | -10 °C to +50 °C | -10 °C to +50 °C |
| Ambient pressure range | 65 to 108 kPa | 65 to 108 kPa | 65 to 108 kPa |
| Humidity range | 10 to 90 %RH | 10 to 90 %RH | 10 to 90 %RH |
| Battery type | 9V - 6LR61 | 9V - 6LR61 | 9V - 6LR61 |
| Battery life | > 20 hours | > 30 hours | > 30 hours |
| Adaptor - 1/4" * | Nor 1444 | Nor 1444 | Nor 1445 |
| External supply voltage | 7.5 to 15 V DC. Automatic shut-off when V < 7.5 V DC |
| CE classification, EMC | EN 50081-1, EN 50082-1 |
| Safety | EN 61010-1, 1993 portable equipment pollution category 2 |
| Size | Length: 109.5mm, Ø: 40 mm |
| Weight | 185 g with battery |
| Controls | Power-on push button with green LED indication |
| E&OE - specifications subject to change without notice. |
