There are two basic types of hooks, on-locking (standard) and locking. Locking hooks are fairly new and there are several designs out there. The primary purpose for the locking mechanism is to increase the amount of weight a hook can hold (the lock keeps the hook from opening) and to prevent the hooks from coming out (for example, if suspending from great heights).Standard hooks (fishing hooks) are definitely the most commonly used design for suspension. They are cheap, easy to find, and quite durable. These hooks normally come in two forms: open and closed eye (the top opening where the rope is connected). Closed eye hooks are probably the most common in that the rope it less likely to come detached, although open eye are useful in situations where rigging quickly is a concern.