This is a good quality leather slipper or Devon stirrup.
Such stirrups were used before the development of safety stirrups - the enclosed toe prevented the rider's foot getting trapped in the stirrup, so they would not be dragged in the event of a fall.
The stirrup has a steel frame and is covered in mahogany coloured leather with a decorative stitched seam around the opening of the toe.
The leather is missing from half the suspension arch, exposing the steel below. The metal shows surface oxidation, but is quite stable.
There is a split in the back seam of the sole.
Unusually this stirrup still has its original leather strap - it predates the special safety bars and straps seen today.

Dimensions : External Width 3½" (9cm), height 5½" (13.8cm), length of tread 9" (23cm)