... well Gyro Units are ment for the Mini-Z cars i believe... i put mine on both MX01 chassis Mini-Z 4X4 Crawlers. Obviously they are ment in racing to counter steer so your back doesn't goes off the track no loosing traction or in drift doing mad stuff. On those Crawlers they act a bit differently i mean those Crawlers don't run very fast. So in my opinion thay are more useful in side climbing they easy to roll over and the Gyro helps you to avoid that by blocking power and do some small adjustments. I m happy with i mean the moment i bought those 2 Crawlers a few days later i wanted to upgrade them all, you know what i m talking about, if we love this things we always want do go farther. A Gyro can be a move in that way.