backpacks for airline travel Amazon’s No. 1 Carry-on Backpack Has a Sky-high Rating From Flight Attendants—and It’s Only $25 The waterproof backpack will Color:M760X72 Bass Pole Mate2

backpacks for airline travel Amazon’s No. 1 Carry-on Backpack Has a Sky-high Rating From Flight Attendants—and It’s Only $25 The waterproof backpack will Color:M760X72 Bass Pole Mate2

Bass Pole

My best guess is that one of the moving parts inside binds in one direction and stays there held by friction, then during tightening the tension of the spring reaches a certain level that overcomes the friction holding the binding part so it slips then stops at the opposite limit of its clearance

Mate2

Color:M760X72

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