Bent Leg Safety Stirrup Irons.
These safety stirrups, also known as the Australian simplex,
allow your foot to slide out quickly to prevent you getting dragged along in the event of a fall.
They are ideal for all levels of riders, particularly those riding novice horses.
To measure the size of stirrup
you need measure the width of your foot whilst wearing your regular riding boots and add on 1.25cm of space to either side.
This will give you the width of stirrup iron which you require.
The cottage craft Bent Leg Safety Stirrup Irons are made from Stainless Steel.
and are available in a range of widths.