The primary function of a retractable block is to arrest a fall by quickly activating the braking mechanism when it detects sudden movement or acceleration. This rapid response helps minimize the potential for injury due to a fall. Retractable blocks are designed to maintain constant tension on the lifeline, helping to minimize slack and reduce the risk of tripping or entanglement during use. Also, it's important to note that the specific features and capabilities of self-retracting lifelines may vary depending on the model, manufacturer, and intended use. When selecting and using an SRL, it is crucial to follow the manufacturer's instructions, conduct proper training, and adhere to applicable safety standards and regulations.