WTB: 2X macro focusing converter K.mount

Looking for a2X Macro Focusing Tele Converter for Pentax K. Had one of these before and must have mis-laid it somewhere. Anyone have one to sell? Mine was a Vivitar like one below (borrowed photo from the web).
Cheers,
Mats

Does it need to have the A contacts on it?

Hey Mike.
Well, not really.. The one I had didn´t have them and I metered with the green button. But it would´t hurt to be able to run in A-setting. You have one?
Cheers,
Mats

I have one of each but would rather keep the one with contacts.

That´s understandable. I´ll drop you a PM.
Cheers.

There is a Pentax K T6 2X with case on Ebay right now. It's a very good rear converter for green button metering

Actually there's two UK ones listed presently, but they're not the Vivitar macro. Is there any advantage in using that over extension tubes?

The macro focusing teleconverter is 2X telconverter with adjustable macro extension. The K T6 2X rear converter is a teleconverter only.

Edit: Some people have removed the optics in these for using it as an adjustable macro extension only, like the Helicoid Extension Tube K
http://www.bdimitrov.de/kmp/misc/macro/ext_helicoid.jpg