The top one is a part of ALPA extension ring, the bottom one is M42->E adapter/ring(CMHT) in the previous photo. This of course gives your alpa-mount lenses infinity focus. (This one does not use any ext. tube, only use the both ends.) See > http://www.pbase.com/kkawakami/image/155583910 ALPA ext. tube set > https://pbase.com/kkawakami/image/150880436