Multi-function illuminated commercial propulsion control head.
The 6555 is an illuminated control head, constructed from bronze and stainless steel but for interior use only. The 6555 typically comes mounted on a 4 switch base, allowing for similar functionality as the 6508.
The 6510 can be equipped with two potentiometers per handle to act as a fail-safe, typically requires a control base and is not considered water tight. The photo shown is a 6555 installed onto a control base.