The Push Button or Plunger actuated PB series was developed as a direct replacement of an existing and problematic mechanical type contact. The PBF flange push button can be installed without re-drilling or redesigning the original installation. The sealed contacts of the reed switch insure a long service life. Plunger actuated reed switches have become so popular on new installations that many variations are now being produced. Also known as -G.R.I. Telemark Corp. 3/ 4 D PLUNGER FLANGE LEAD WHT - GI-PBF100W