Launch Lugs

A launch lug is sized to slip over the launch rod on the rocket's launch pad. It provides stability for the rocket as the rocket lifts off by forcing the rocket to remain parallel to the launch rod during the first seconds of flight. This allows the rocket to build reach a high enough speed and gain enough momentum the be stable in flight.

Rail buttons serve the same purpose as launch lugs. Instead of sliding over a launch rod, a rail button fits into a rail. Rails are stiffer than launch rods, providing better support during the initial stage of the rocket's flight.