The info given in Peter Hofschröer's Osprey on Prussian Cavalry is correct.

The only bit of info missing there is that an order of the king of 30th April 1809 had stated that the regiment should continue to have white piping, knots and barrels on their yellow waist sashes, "as yellow buttons on yellow cords do not constrast well".

The uniform prescribed for the 1. Schlesisches Husaren-Regiment (it received the number 4 as late as 1816) was the uniform of the dissolved Oberschlesisches Husaren-Regiment (named Husaren-Brigade Dziengel until 1808), whose distinctions were in turn identical to those of the former Husaren-Regiment Fürst von Anhalt-Pleß (1806: Husaren-Regiment Schimmelpfennig von der Oye, with the semi-offical number 6).