There is a gasket... which i got from autobarn or something for like <$10 can't remember but apparently honda sells them for something like $20

OEM is standard and if it breaks it just lets coolant thru regardless of temp... so its hard to warm up your car to run and normal temp... and last at least 5-10 years?

Unless you race alot and want to go aftermarket which will release at a lower temp.