In addition I have ordered this adapter can adapt what M42 lenses. The adapter has a suitable screw thread, in which the old lens is screwed. Importantly, not all not all lenses with thread, there is also M39 and T2 screw! Therefore nachgucken precisely before buying whether you have the correct adapter.
The adapter is on metal (aluminum) and does not contribute too, but has appropriate weight. Sharp bone I can not tell, and the adapter can be easily put on the bayonet.
The turn to infinity is generally possible, you should test its adapter but precisely because it can come by manufacturing tolerances mean that it is not possible to infinity, or sharpen the focus.
The shipping takes a while but is given realistic. After all, it ends up directly in the mailbox, so one does not have to wait for the delivery man.