When it comes to using a lever handle, there are a few additional components you may need, depending on the specific application or context. Here are some common items you might require:

1. Door: If you plan to use a lever handle for a door, you’ll typically need a compatible door itself. This can be a wooden, metal, or glass door.

2. Lockset or latch: To secure the door, you’ll likely need a lockset or latch mechanism. This can include components such as a strike plate, deadbolt, or latch bolt that work in conjunction with the lever handle to lock and unlock the door.

3. Keys or access mechanism: If your lever handle is part of a lockset, you might need keys to operate the lock and gain access. Alternatively, for electronic or keyless systems, you may require an access mechanism such as a keypad, keycard, or biometric reader.  Usually, most locksets will come with a key included but double check manufacturer parts list to be sure.

4. Mounting hardware: Depending on the specific lever handle and the type of door or gate you have, you may need appropriate mounting hardware. This can include screws, bolts, or other fasteners required to securely attach the lever handle to the door or gate.  Usually, these will come included with the door handle, but it would be prudent to check manufacturers’ guidelines to be sure.

5. Backplate or rosette: Lever handles often come with a backplate or rosette, which serves as a decorative and functional component. It provides an aesthetic cover for the installation area and can also help to protect the door’s surface.

6. Spindle and set screws: The lever handle is typically connected to the lock or latch mechanism via a spindle, which transfers the motion of the lever to the internal mechanism. Set screws are used to secure the lever handle onto the spindle.  These will come included with most door handle sets.

7. Tools: You might need a set of tools to install or adjust the lever handle, such as a screwdriver, drill, tape measure, and possibly a chisel or router if the door or gate requires modification for the handle installation.

8. Hinges:  To fit or hang the door itself, you will need hinges.  These can vary in shape, style, weight tolerance and size depending on the door size, usage of the door and door weight.

Remember, the specific requirements may vary depending on the type of lever handle, or door, and the intended use. It’s always advisable to consult the manufacturer’s instructions or seek professional assistance to ensure proper installation and functionality.