Having a second hand-piece and potentially even more, allows a lot of flexibility to "quick change" bits when working. I am a little concerned about how easily they snap in and out from the shaft. It's not an issue yet, but I can see how the mechanism might "loosen" to the point where they no longer stay connected to the shaft. Time will tell. I am using them on a Grobet S-300 tool.
Reviewed by: Jim Barbieri from Davenport WA.