Which type of collar is least reliable for restraint?

The nylon collar is considered the least reliable for restraint primarily due to its design and materials. Nylon collars are typically flat and do not have features that provide additional control or a secure hold on the dog. This can make them ineffective for strong, active, or determined animals that may pull or attempt to escape.

In contrast, other collar types like the martingale collar and training collar are designed specifically to provide a more secure fit and greater control over the animal by adjusting tightness when the dog pulls, which helps prevent escaping. The promise collar, while not as commonly used, is typically designed with training and correction in mind, making it more reliable than a basic nylon collar.

Overall, for effective restraint and control, a collar needs to incorporate features that ensure it remains secure during activity, which is often lacking in a simple nylon collar.