Not very good, fine for lower power applications but DEFINITELY not 40a. They work but I wouldn't trust them, also shipping accounted for nearly 40% of the price of them. Bought locally for 16€ a better one, much more promising than these at 10€ a pop. It's nice that they come with a heatsink though, but the wiring provided is just so thin it's sad. 220v at 3a they were fine, but I didn't dare try them with my keenovo 2.4kw unit as that would peak at more than I was comfortable putting these relays at.
All good