Review on Optimized Mercruiser Thunderbolt V8 Distributor Cap Rotor Spark Plug Wires Kit Set 5.0 5.7 7.4 8.2 350 by Doug Ellingson

The description gives the impression that this is a Mercruiser product but it is not. It's a kind of after-sales service company. Probably made in China. The connector heads on the distributor cap appear to be brass, but that is the only brass metal part. The retaining screws are probably chrome steel and the distributor wires are some metal other than brass - maybe aluminum I'm guessing. Don't expect it to last as long as a genuine item.