What is the proper way to attach two slings together?

The correct method to attach two slings together is to use a shackle. Shackles provide a secure and reliable connection point because they are designed specifically for rigging applications. They can handle heavy loads and provide a significant safety margin, making them ideal for joining lifting equipment like slings.

Shackles come in various types, such as bow shackles and D shackles, and are made from strong materials that ensure they can withstand the forces involved in lifting operations. When using a shackle, it's essential to ensure that it is properly secured and load-rated for the specific weight being lifted, which adds to the safety of the entire rigging system.

In contrast, other attachment methods like using a bolt or a clip may not provide the same level of stability or security in a lifting environment, potentially leading to unsafe conditions. A hook, while sometimes used in rigging, is typically not ideal for permanently or securely joining two slings, as it can easily disengage under certain conditions unless it has a locking mechanism. Therefore, utilizing a shackle is the best practice for securely connecting slings.