Shackles are metal pieces secured with bolts, pins or spring connecting items together for rigging. They have many industrial uses, but very common in the ship. It is very important for people who own or operate ships to understand their strengths and limitations.
On the ship, they are doing everything from securing the anchor to hold the line rigging. Their forms are usually allowed the objects to move to push and pull from multiple directions without creating destructive power on the device. You can find 3/8″ Adjustable Stainless-Steel D Shackle from various web sources.
The most common method of fastening the bolt or pin shackles. Each option has advantages and disadvantages. You may have a particular need or use that will help you choose one over the other.
One-shot has a set of threaded loops allowing it to withstand close, while the pin just slides through the opening and is secured on both sides.
You may find that the spring shackles are most useful to you. They have a system of springs or tension in a place that allows you to open it without removing the pieces connect. Bolts and pins are not usually found in this type. You have to tap into it to open the gate.
This is a safety measure that will prevent the load from coming loose from the connection. It is important to understand how heavy the load you plan to take so that you can choose the right hardware to get the job done.
If you are not sure of the weight, it's better to be safe than sorry. Be sure to have the hardware far beyond the carrying capacity typical of you are on the safe side. Avoid standing directly below each of your cargo lift.