The pcb mounts on the front panel of the machine on two screws. The red lense is 98mm wide and 120mm height. For example, ones for AC/DC tigs, wire feed speed read out, etc.
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Similar high-current shunt ammeters are also available on eBay:
1 X 200A/75mV Shunt. --Display: 0.28" LED digital tube. --Panel cutout 45.5x26.5 mm. --Current: 500A. --Size: 48x29x21 mm. All products are quality checked. We will be happy to resolve any issues you may have in a cordial and friendly manner.