I received this Vivitar extension ring in a box of stuff, and have no use for it. It's pre-AI, with a prong coupling only and provides 12mm extension for mild close-up work. It's in good user condition, everything (meter coupling, auto-aperture shutdown thingie, and mount release) seems to work smoothly.
$7 will get this to you in the US.
$7 will get this to you in the US.