There are no UL Listed compatible connectors made by different manufacturers. The UL standard allows for it but only at the request of both manufacturers and Stäubli, who makes the MC4, does not want to be compatible with any other manufacturers' connector. Of course, most of the other manufacturers want to be compatible with MC4 so people will buy their connector. So they reverse engineer MC4s and make theirs close enough so they click together, this leads to the "if it clicks it fits" mentality. It can also lead to fires and melted connectors. Some manufacturers will just put MC4 Compatible on their datasheets and hope no one asks. Some have gone to the trouble of having independent labs test the compatibility and issue a letter saying they were tested and are compatible. But there are no UL Listed compatible connectors. Mate connectors between different manufacturers, even if they click, at your own risk and I recommend against it.