I believe that is a Thayer action. The 'knuckle' is elongated to span the repetition lever and jack surfaces. It works well but replacement parts can be a challenge. I service a restaurant with a Behning grand with these and the hammers and centers are getting worn out. To meet their budgeting concerns, I am hoping for a grand from which to salvage s/f/h and reps. -- Regards, Jon Page
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