N. Brondoit & Cie, rue du Chou, Herstal.
Manufactured by Bayard-Brondoit (aka Brondoit Herstal) 1895-1929 in Herstal and Leige.
Nicolas Brondoit built 97cc two-stroke bicycle attachment engines before and after WWI named Ideal-Brondoit, and in 1922 produced the Brondoit motorcycle. It won the 250 class of the 1925 Bol d'Or.
Paul Le Bussy joined the company, and in 1926 350cc and 500cc MAG models appeared. Le Bussy died during a practice session and the company did not recover from the shock.
Sources: François-Marie Dumas, Wikipedia NL, period advertising.