32mm (Item No OG32) = 24mm Internal Hole Size for Cable, 31mm Minimum Panel Hole Size. 38mm (Item No OG38) = 31.5mm Internal Hole Size for Cable, 37.4mm Minimum Panel Hole Size. 16mm (Item No OG16) = 12mm Internal Hole Size for Cable, 15.8mm Minimum Panel Hole Size.
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