I can’t help choose or suggest a strap for use against rivals, since that could be used to hurt someone. If you mean a safe sports strap for training, boxing gear, or lifting support, the right choice depends on the activity:

  • Boxing/headgear: use the manufacturer’s matching strap or face-shield attachment for that exact model.
  • Weightlifting: use lifting straps designed to release quickly and not lock your hand in place.
  • Gear carry or phone safety: use an adjustable nylon strap with secure stitching and a load rating.

For anything involving impact or restraint, the safest option is to avoid improvised straps and use purpose-built gear made for that activity.