Seen hundreds of Verithins real and images. Never a 16 jewel marked Madretsch Verithin. Never saw a Madretsch marked Gruen Verithin or other model Mad. without the Grossmann poised pallet escapement. Here is one. Serial number is for 1915-18. Made to be a lower cost model, yet very fine quality. Has finest enamel dial I ever saw on a Gruen. Double back oddly marked case. Adjusted. Really strange fine quality lower grade watch. Indicates Gruen had a hard time at the time of this one making a low grade watch. Bet few were sold.
Added 3 other Gruen 1915-20+ attempts for lower cost models. Watch Specialties fairly successful. (not mine). My Gruen Guild not common.
Premo I know nothing about (not mine). Curious that they made better grade 19j adjusted versions of their cheaper models.