Perfect fit, easy replacement if one has some skill and a small soldering iron. However, is not always the Accu defective, it can also be the charging electronics. The handpiece have to open first time and measure, or test with another Accu. Instructions for Accu exchange is available online. Here only 4 stars because the solder tail of accus is too wide a bit, and will have to be reworked to fit through the slot in the board. However, there is no problem with scissors.