Single groove Collets

Hi Guys, this is my first post and I hope someone can help out here.

I am rebuilding the 1.3 engine for my son's Mk1 Golf, however, the new valves that were supplied take a single groove collet but the ones that came out are a 3 groove collet so I am trying to locate the single grooved collet type if I can, any ideas where I can get these from?

I did locate some in the States using the part number but nothing in the UK or Europe via Google. I would have sent the valves back and tried to exchange them for the 3 groove type but it was over 2 years ago since we purchased them and didnt notice the difference at the time, but now have the time to get this thing back together now so new collets would be the cheaper option rather than purchasing new valves again.