Have looked on the Bestfittings web site everything but a walther one. http://best-fittings.co.uk/airgun_fillprobes.asp
I think "best fittings" have parts that are not shown on there site but can be found on their ebay listings. http://cgi.ebay.co.uk/Walther-Fill-Adaptor-Hard-find-1-8BSP-thread-/250754162463?pt=UK_SportingGoods_Hunting_ShootingSports_ET&hash=item3a621cdf1f