The envelope is just like flapping discs, they're attached to a spindle of an angle grinder and set according to its parameters. Industrial ellipse grinders are applicable in broad industries and the flap wheel are specifically developed to comply with its working features. So called flap wheels are usually constructed to fit the spindle of an angle grinder, withstanding its rotor turn up to dozens of thousands of rotations per minute. Such tools fluff work of milling, polishing and cleaning. In Construction, workers use angle grinder mounted flap wheels for concrete grinding, metal bar cutting and edging, as well as cleaning rust off metal parts. Due to portability of angle grinder, flap wheels, and the nature of angle grinding, these tools enables highly efficient and effective small scale on site grinding tasks.