The Gemini Gyro by Yomega is a yo-yo first released in 1990. It features a transaxle for long spin times, but its defining gimmick, is that it could be converted into a spin top and back. It is done by unscrewing the halves, and putting a special plastic shaft, referred to as the "power converter" on one of them. To make the top spin, the user would wind the string around the power converter, insert the yo-yo half with the axle into it, pull the string swiftly and lift the axle half off of it. Sadly, the Gyro Gemini yo-yos did not do too well in the market, and is difficult to find these days.