Embroidery hoops are a great tool when you're repairing garments. By stretching the worn garment over a hoop, applying approximately the same tension as when you wear the item, you will more easily achieve a smooth and neat final result, whether you are darning, patching, or decorating.
Oval embroidery hoops can, of course, be suitable for oval motifs, but the main reason we have chosen to stock these is due to wear and tear, especially on elbows, but also on knees. The small round embroidery hoops we sell, in 7.5, 10, and 12.5 cm, can work to stabilize areas like elbows, for example, but my experience is that the wear is often larger than can be fixed with a circle. The wear is usually more elongated and not as wide. This is where oval hoops are great; you can stretch a larger worn area without the sleeve or pant leg you're working on needing to be so wide that an embroidery hoop as wide as the damage is long would fit in the garment.