The BU-51C-2 is a solid copper meter testing clip (BU-51C) with Mueller's BU-49-2 flexible PVC insulator. Connects to wire up to 14 AWG via crimp or screw connection.
The BU-62 series of flexible PVC insulators are used to electrically insulate BU-60, BU-60C, BU-60S, BU-60CS, BU-60TBO, BU-60X, and BU-61 series clips.