Are U-lock "wheel extenders" sold separately? I quite like the Kryptonite U-lock "wheel extender" idea - but I'm less attached to Kryptonite as a company - and even less so to the Messenger series of their locks, which is the only one that has this feature. 



Are these wheel extenders available separately? I can't find them as a separate item on Kryptonite's website and don't see anyone else offering them either. Are they called generically something else?
Kryptonite does not sell that separately right now(source: am a Kryptonite distributor), but I'll bring it up to them, see if they are interested in offering it.