www.GarvinIndustries.com – 4″ set screw electrical couplings are used in dry locations to connect the ends of two 4″ EMT thinwall conduits together to extend the raceway. Garvin Industries’ steel set screw couplings provide concrete tight connections when taped and properly secured with the included set screws, and are rated for electrical applications above 600 volts. Their heavy gauge steel construction maintains mechanical protection and solid grounding of one conduit to another. They are also zinc electroplated for excellent corrosion protection in damp locations. Set screw couplings are made with a versatile combination head screw that can securely fasten one conduit to another using a slotted, Phillips, or Robertson head screw driver.
Product Page: https://www.garvinindustries.com/electrical-fittings/emt-conduit-fittings/set-screw-couplings/sscp-400
Garvin Industries Homepage: https://www.garvinindustries.com
The US is one of the only countries using the Imperial SAE sizing system for nuts, bolts, screws, washers, etc. The rest of the world uses the metric system. Metric sizes should be abundant and CHEAP! I found otherwise looking for exact types & sizes for an import auto restoration project. I also learned the hard way about hardness grading.