These are "EXPANSION" plugs, NOT "Freeze Plugs"!!! They are called "EXPANSION" plugs because you hit them with a ball pein hammer and they EXPAND into the core hole and plug it. They actually plug the core holes where the core was suspended in the sand mold during the casting process of the block in the foundry. DON'T EVER expect them to protect a block from freeze damage!! Unless you're damn lucky, THAT nutty idea will cost you a broken block!! Kurt Kurt Greske ( kurt_greske@xxxx )