The Ram´s Head Muff was the second version of the Muff. It featured a bigger enclosure and had a little head logo on the enclosure, so the nickname.
Installation Guide: installationguideV001_en
Parts list (BOM): rambomenv2_2
Schematic and pcb: muffv2schalt
Docs for version up to 27.04.2106:
Parts list (BOM): rambomenv2
Schematic and pcb: muffschalt
Wiring layout: muffwire