At home, 36" two piece aluminum 1/8" and 3/16". I never take them apart, but I did sand them ever so slightly at the joining ends to prevent a lip that the lugs could hit.

For my rack launcher used at schools, it's 1/8" x 36" steel one piece rods. I just wipe them and coat them with grease so they won't rust for the next year's launches.

When I did HPR it was usually 1/4" x 4' and 1/2" x 5.5' or 6' stainless. I still have them, but haven't flown HPR in a long time. For my largest rockets, I used my buddy's big rail pad. It was probably 8 or 10 ft long. I don't remember now.

Just FYI, a lot of the 1/8" Estes rods in more recent times are only about 32" long.

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I love sanding.