Abstract: Use of a snap hook requires the capture loop to be cradled in a joint of the index finger to prevent it from rolling in the hand. Hooks having a cylindrical body roll easily, and those having an oval section capture loop, roll more easily. When a hook rolls, its loop can move to a position where it blocks access to the gap, requiring it to be repositioned in the hand. Ergonomic requirements provided in this hook include: spacing the hand a maximal distance from the gap, stability from rolling in the hand, and minimal movement of the hand members in operation. The hand does not close around the hook; it may be held between the thumb and a finger, a natural configuration in which the hand retains the lie of its usual open form. Stability from rolling results from the forces of contact being directed within the borders of the wide contact surfaces of the body and the button. The larger the contact forces, the more stable the hook is.

Abstract: Use of a snap hook requires the capture loop to be cradled in a joint of the index finger to prevent it from rolling in the hand. Hooks having a cylindrical body roll easily, and those having an oval section capture loop roll more easily. When a hook rolls, its loop can move to a position where it blocks access to the gap, requiring it to be repositioned in the hand. Ergonomic requirements for this hook included: spacing the hand a maximal distance from the gap, stabilize it from rolling in the hand, and minimize hand movement in use. The hand does not close around the hook; it is held between the thumb and a finger, a natural configuration in which the hand retains the lie of its usual open form. Stability from rolling occurs from the contact forces being within the wide contact surfaces of the body and the button. The larger the contact forces, the more stable the hook is. By its nature, it does not roll.