The st90s digital throttle was another good and very noticeable feature. The plus and minus throttle buttons are arranged just above the thumb and are good for when you need to speed up in a hurry. The throttle has 5 positions and clicking the plus button raises the throttle to the next position (indicated by 4 green leds above the throttle), or you can hold it down to increase the throttle at a slower (though constant) rate the revolutionary foldable stick for professional gaming performance. Easy installation and configuration; incremental or progressive throttle control gives maximum flexibility. Features: rapid-fire trigge. 2 Fire buttons. 4-Position digital throttle with led indicators. Single spring gimbal mechanism ideal for left- and right-handers. Retractable tripod legs for maximum stability and easy storage. System requirements: pc pentium 133mhz or higher with usb port / microsoft windows 98, me,2000 and xp / directx 8.1 Compatible.