the apparatus is for my wife. now she has ersatzbuersten needed. they went to but the plugs with the small hole in the middle were not there. these are the plug with a small hole in the middle to pressure inden apparatus so that they are fixed. in the apparatus a small pin is where the brush with the plugs and the hole inden stylus pressed is so it holds. but as I got the brush can not. perhaps koennensie times look. the apparatus is great my wife says. recommended