The original manufacturer of Eastwood's pants belt is not known. This knowledge seems lost to time since both the director and the film's costumer have both passed away. It may have been purchased by Eastwood in Los Angeles and brought with him to Spain.
It appears as though it was the exact same pants belt his character wore in the TV series Rawhide.
Eastwood's pants belt is tough to get a good look at in the films unless you examine them frame by frame. The buckle's looks to be both silver and brass finishes depending on the scene and the color grading. But the buckle is definitely a brass finish.
Curiously, Eastwood consistently wears his pants belt in the opposite fastening direction of his holster. This seems to be the case in all of Eastwood's films and in Rawhide. It can only be assumed that this is a personal preference of Eastwood's.
The leather is plain brown distressed leather and has no embellishments whatsoever. The length is very short and the belt's end *just* clears the buckle. The belt's end is rounded and doesn't even reach the first belt loop of his pants.
The buckle is rectangular in shape and not square. Its finish is smooth worn brass.