Welcome to Hercules/Sachs parts. Other German-made mopeds are Kreidler, Kynast, Odyssey, Solo.
In Germany, there are two kinds of mopeds:
Mofas are 25 km/h (16 mph), no licence required, minimum age 15, no passengers.
“Mofa” is short for motorisertes fahrrad (motorized bicycle).
Mopeds are 40 km/h (25 mph), drivers license required (any class), minimum age 16.
This is why Sachs 504 and 505 engine cylinders say “40km” or “25km”.
Hercules made in Germany by Hercules Sachs 504 or 505
Hercules makes the Sachs brand moped, while Fichtel & Sachs makes the Sachs brand engines. Many other non-Hercules makes have Sachs engines, such as General, Foxi, Colombia, etc. Having a Sachs engine does not necessarily mean the bike is Sachs.