An abutment and spring gate mechanism is placed within the arcuate channel to prevent a relatively rigid wire formed into an arcuate shape from being used to release the attaching assembly part.

• 在弧形通道内设置有支板和弹性闸板机构，以防止有人利用做成弧形的刚性较大的金属丝来松开固定机构的上述部件。