The idea behind the original high-speed rotary tool, which was released by Albert J. Dremel in 1935, was to rotate a bit at faster than previously capable speeds; with the bit being kept in place within a collet chuck.
The concept behind the original Rotary Tool was to rotate a bit/accessory at high speed with the bit being held in a collet. Variable speeds differentiate between machines and they usually cover a range of 3,000–37,000 RPM.