They are attached to the transom

Cutout diameter: 57 mm

and the opening can be closed with a cover

5 volt battery

88 mm outer diameter

KartenWerft Binnenkarten ATLAS 12 Main und Main-Donau-Kanal Dropshipper Ware They are attached to theThe KartenWerft Inland Map Atlas 12 covers the waterway area around the Main River from Mainz to Bamberg and the Main Danube Canal via Erlangen and Nuremberg to the Danube. Atlas scale: 1: 40. The Inland Map Atlas 12 offers, among other things, professional cartography in an attractive layout, a product key for activating the digital inland maps in the KARTENWERFT NAVGO app for Android and iOS, and a 365 day area service for updating all area