Which type of pliers can be adjusted to lock in a certain position?

Slip-joint pliers are designed with a unique mechanism that allows the jaws to adjust to different sizes of objects, effectively locking into a specific position when needed. This locking capability is facilitated by a pivot point that enables the jaws to open wider or closer together based on how the handles are positioned. This feature makes slip-joint pliers particularly versatile, as they can grip various shapes and sizes securely, which is especially useful in many automotive and shop tasks.

In contrast, the other types of pliers mentioned do not have this adjustable locking mechanism. Curved-nose pliers are primarily used for gripping and twisting wire and have a fixed jaw size. Cutting pliers specialize in cutting wire and do not have an adjustable feature. Long-nose pliers are designed for reaching into tight spaces and gripping small objects, but they also lack the adjustable locking capability that defines slip-joint pliers.