Result: Fits, does not wobble - and after measurements with collimator quite well adjusted - both the centering and the squareness of the bearing are given, as it should be. Moreover, in my fast screwed 135mm f / 1.8 is also true the Infinity brand, so the length appears to be correct.
Quality and price-performance ratio: building might not be quite so wertig as an adapter of Novoflex - but is more expensive by far, the price-performance ratio of the adapter sold by XCSource is very much better.
Summary: For the money an absolute buy recommendation.
Addendum (2013-Sep-28): The adapter does not appear to with all NX models and firmware versions - with some combinations the camera expects a chip in the lens, and does not fire if one does not exist (Error message: "Check Lens ! "). This is not a mechanical problem (Nichtbetaetigung the signaling switch in the bayonet, which occurs in many other adapters, in which are too thin "bayonet fins" to betaetetigen the switch) - the adapter is detected, but the trigger does not take place, since the recognized "objective", in other words, the adapter, the absence of chip does not communicate ... However, the adapter has with me always work with the latest firmware in position "A" and "M" - tried to NX10, NX100, NX200, NX300, NX1000 ,
Have about 100 recordings made with the NX1000 and a borrowed NX300, the adapter and some Zeiss and Pentax M42 lenses on the last weekend - with very good results. The starting price even for good M42 "waste glass" is currently (still) very favorable - working with the manual adjustment of distance and aperture may not like any, is somewhat more complicated than with a classic SLR, but has the advantage that one to detail involved in the art work, rather than simply draufloszuknipsen. Today we continue with a Schneider Xenar and the NX100 - Portaits in vintage look ...