hobbit Definitely test your putter with a magnet from the fridge before buying.
Magnetic ball markers can be a bitch if the magnet is in the marker. Put the marker down, lift the ball, tap the marker (why do we do that?). Some putters (Ping Darby in my case) make the marker jump from the ground onto the putter. Lucky it wasn't a comp or I'd have been looking at a penalty ...