From Second Life Wiki
Bodyparts in Second Life are objects your Second Life avatar needs to wear and can't take off. However, body parts can be exchanged.
Bodyparts are stored in the Bodyparts inventory folder () by default, when created or received.
Items belonging to the category of bodyparts are:
You can create new bodyparts by opening your inventory (how to change your appearance.- ) and by choosing a bodypart via Create > Body Parts. These can be worn (via double click or right-click → wear) and modified via Edit > Apepearance.... See also