Modifiche

[[File:Columbus-65-Black-Knob.jpg|thumb|A Columbus 65 ''knob'']]

[[File:Columbus-65-Black-Knob.jpg|thumb|A Columbus 65 ''knob'']]

We should speak more specifically of a  ''knob'' in all those cases in which the [[case back]] of a pen is not simply the end of the barrel, and is not used as a decorative element or as a [[blind cap]] for protection of the [[filling system]], but is instead a direct component of the latter, with the role of part of the device on which one must act to activate it.  

We should speak more specifically of a  ''knob'' in all those cases in which the [[case back]] of a pen is not simply the end of the barrel, and is not used as a decorative element or as a [[blind cap]] for protection of the [[filling system]], but is instead a direct component of the latter, with the role of part of the device on which one must act to activate it.

Therefore, the bottoms of classic [[piston filler]]s are classifiable as such (not those used to protect a knob underneath), the knobs of [[plunger filler]] system, those of [[safeties]] and also those of some specific types of [[button filler]]s (like the [[push-knob]]). In all of these cases the ''knob'' is a constituent part of the pen's filling mechanism, and is used for handling. A photo gallery can be found on [[Knob_Gallery|this page]].

Therefore, the bottoms of classic [[piston filler]]s are classifiable as such (not those used to protect a knob underneath), the knobs of [[plunger filler]] system, those of [[safeties]] and also those of some specific types of [[button filler]]s (like the [[push-knob]]). In all of these cases the ''knob'' is a constituent part of the pen's filling mechanism, and is used for handling. A photo gallery can be found on [[Knob_Gallery|this page]].