[Gearhead999]

AS nastyyn8 said above the 1/8 is smaller.

You don't NEED a ring expander to install them, it just makes it easier. I personally don't use one. I thread them.

Now, you have to be very careful, cause the rings are very hard and brittle and will break easily. Also, don't nick or scratch the piston as you're installing them.

Take your time filing them. It is very easy to file too much off.