What is the unique feature of push-pull pins?

The unique feature of push-pull pins lies in their design, which incorporates moveable components that can expand or contract to securely lock the pin in place. This mechanism allows for quick and easy fastening and unfastening, making them ideal for applications requiring frequent assembly and disassembly. The pin can be pushed to engage or pulled to disengage, providing a straightforward method for securing components without the need for tools.

While other options touch on different characteristics of fasteners, they do not accurately capture the distinct functionality of push-pull pins. For instance, they are not intended for permanent installations, as the design emphasizes ease of removal and reusability. Additionally, push-pull pins are not specifically meant for threaded assemblies, which typically rely on screw-type fasteners to achieve a secure hold. Lastly, while push-pull pins do not require additional components for their locking mechanism, this aspect is more of a convenience rather than a defining feature that distinguishes them from other types of fasteners.