It allows M42 aka Praktica or screw mount lenses, which can be identified with the screw threads on the back, to be used on Konica Autoreflex cameras, hence K/AR.
On this site, I post lots of macro shot with M42 lenses like the Industar 50-2 and the CZ Biotar 55mm f1.8. I am able to do this because the "Konica Praktica Lens Adapter" can fit onto the Nikon F mounting of my Nikon D40.
It is a loose fit and there is no infinity focus but it is fun to use in a gear head's version of a mashup.
Hence, I can have an Industar 50-2 with an adpater ring going to a heavily brassed black Konica Autoreflex T3 (with a Yashica Tele-Wide finder for good effect).
The adapter ring is not easy to find and is one of my more treasured items. It allows me to marry the solid metal shutter awesomeness of a Konica SLR with the variety and weirdness of all the M42/Praktica/Screw Mount lenses out there in the world.
Just remember, though, don't mix it up with a L39 lenses. Or, ahem, you'll be screwed.