I would suggest in some circumstances these do not work out as the best solution.
There needs to be adequate gap between the propeller and cutless bearing for a free flow of water to flood and circulate in the bearing and I feel 2mm does not meet this requirement. In fact one only has to do an eyball survey around a marina to see that most folk agree with me and it seems that a normal gap is around 2/3D on a 1" shaft .
If the propeller sits inside a cut out then this also may be a determining factor