They are no longer made, I would see if you can find a good used one, 7240.260 or the later but also out of production 7240.270 would work. We occasionally get working used drivers, but we are out at this time. Another option is the 6100.015 kit on the Tunze site which is an upgrade to the current 6105, in place of magnet holders it includes an adapter clamp to work with the holder you already have.