The MGN09135 is a D0 gauge from the Merlin Gerin D0 range, designed as an installation accessory for D02 fuse-switch disconnectors. It accepts associated fuse ratings of 32 A, 35 A, and 40 A, making it the visual and mechanical interface that confirms the correct fuse size is installed in the disconnector base.
The black colour is not cosmetic — it follows the D0 range colour-coding convention that helps panel builders and maintenance crews visually verify the gauge matches the fuse rating at a glance. The three associated fuse ratings (32 A, 35 A, 40 A) mean this single gauge covers a range of overcurrent protection levels in the same D02 disconnector base, reducing SKU count in the stores bin.