New US Manufacture firing pin spring.

Vixen - Based off the original spring and made to a 22.6lb strength. This spring has a internal diameter of .217. There are apparently more than one size, please measure your firing pin to confirm that this will fit before ordering.

L579 - Based off the original spring and made to a 26lb strength.

L61 - Based off the original spring and made to a 26lb strength.

Sometimes called a mainspring, striker spring, or firing pin spring.