The invention relates to a retarder composition for the control of unwanted polymerization reactions during the production and processing of ethylenically unsaturated compounds, the composition comprising at least one di-substituted quinone compound and at least one hydroxylamine compound. The player places an initial wager on an event within the game, and, after learning information about an intermediate outcome of the game, the player is afforded the opportunity to change the initial wager in some manner. The components are configured to allow relative rotation between the actuator and the clutch member while causing them to move axially in synchrony with each other. A ground-based control loop is used whereby a ground-based central controller monitors the EbNo and transmits commands to the aircraft to maintain the EbNo of the transmitted signal within a predetermined range. Some embodiments provide for a quick-release functionality, for example by quickly increasing the gap between the two brake pads so that the wheel can be easilyquickly removed.