Hi Travis,
Actually, it was just a keeper I had laying around but there are different ones available from several manufacturers at any hobby shop. Some have metal ends and others use a hard rubber type grommet. DuBro makes some different types. You could probably find several by searching on Tower Hobbies site. By the way, I had to add 4 ounces of lead the the nose of my 4*60 to balance it properly. The Saito is a sweet running engine, I've started adding more nitro and it seems to like it just fine.
Good Luck,
Bill