Gyro Engine Gear
Spin Gear: Gyro Engine Gear
Weight: 21.2g (including 2x stock plastic bearings weighing 0.04g each)
Must be used with Engine Stopper Base which doesn't support a WD, meaning the fact it is technically the heaviest Spin Gear is mere trivia.
Main EG gimmick is a bearing-mounted gyro section (one interchangeable bearing and one plastic bearing) which can be launched by pushing a ripcord through the base on either side for left and right spin. The Beyblade can then be placed or launched normally while this spins. Consult your rulebook or tournament organizer for legality specifics.
Other gimmick is a switch that holds the gyro part in place, allowing the Beyblade to be launched as usual, which is the only legal way to use this.
There is no real competitive use for this part, however it is a lot of fun, especially if you are able to replace both bearings with Shielded Ball Bearings (the legality of this is unclear),