Where to find a 'Claude Pen'?

From the episode that was shown on August 2nd, Sean Lock had his big 'Claude Pen'.
Does anyone know where I can find one? I don't know what to type in to look up one of that kind. It'd be more preferable if there is one on amazon.co.uk or something like that. Otherwise, it'd be nice to know the official name of the product, if there is one.

"There's a T-Dog in all of us..."