Super-Roc competition comes in both Altitude and Duration versions, but with the added wrinkle of awarding points for length, up to a class-dependent maximum. It's an engineering exercise of sorts; the rocket's airframe must not bend or break during the flight or upon landing, but the points are weighted quite heavily towards max length rockets. So if you build a minimum-length rocket to avoid the potential engineering pitfalls of a very long airframe, it gotsta go a LOT higher (or stay in the air a LOT longer, in Duration) than the competition.
The model shown is a B Super-Roc, and was used for both altitude and duration. Designed around Apogee Component's phenolic tube, it's a very light bird that's won in both events. Using a piston-type launcher, it has reached 200+ meters. In duration events, I rig it with an external shock line, and am able to consistently deploy a 44" parachute made from 1/4 mil plastic sheet. I've almost lost it to thermals, more than once.. Quite a feat in B Super-Roc!