This Hengstler Counter has a six digit display which is electo-mechanical. The counter wheels are advanced by one digit when the solenoid receives a 24 VDC pulse. This counter was most likely used in PLC controls prior to digital counters, but if you want a retro-mechanical look for your project, this counter will do the job reliably. Model number is 0683501, which is embossed in the plastic on the back of the counter and also printed on a Hengstler tag on the product box itself. We believe this is from Hengstler’s 890 series of electro-mechanical counters, as the number 890 appears inside the “H” on the front of the counter. Counter has six pins on back for a wiring harness, but pins 1 & 4 appear to be the active ones (see last photo showing wiring of pins from inside counter).