I use those all the time. They work very nicely for me and how I play. I don't think they are available in different sizes - only different thickness light-medium-heavy as Spidercaster said.
I have never been able to find them here in Holland, but I had a friend bring over a bunch for me.
Robert - I see you are new here. Welcome! I maintain an email list of NL Tele players; we have organized several Tele jam-sessions in the last 4 years. If you are interested please email me and I will add you to the list.
the address is:
jhundt@ziggo.nl