This model was released in the Series III Horses in Action Set #3960, Winners Choice Micro Horses by Creata International in 1998. Breyer bought this mold in 2004. This set was considered a Special Run or Collector's Edition for Specialty Market stores (smaller retail stores). The Series III models had a very short sales run as there were production issues with Creata International.
Sidenote: These models are referred to as Series III or 3 even though the pictured brochure lists them as Series 1. I'm not sure if this was a typo, or if the supplier, The Horse Collector Ltd, listed them that way for their own purposes.
This model was also released in the Series III Stable Estate Playset #3987. Set included 4 Horses and 37 Accessories. The Series III models had a very short sales run as there were production issues with Creata International. The model in the catalog photo looks like the Cantering TWH model, but the only set photo I have seen shows a dark bay Running TB model. These sets have been known to show different molds and colors from the catalog photo. See separate record for the TWH.
This set was considered a Special Run or Collector's Edition, and produced by Creata International for Specialty Market stores (smaller retail stores). Breyer purchased the mold and accessories in 2004.