Most of the fields on the rental page are optional.
The most important ones to fill-in when adding a new item:
Name - What you want to list it as, both for you, and how it’s displayed on the customer quote form. (See Serial Numbers below for appending more to the name)
Category - All inventory gets put into a category, whether you have this feature turned on or not. Check in Settings -> Categories to edit these and turn this feature on/off.
Quantity - If you leave this field blank, we autofill it with a 1 when you save the rental.
Image - This is not required, but if you are using the customer quote form, this is highly recommended. Otherwise, the customer only has the name of the item to go off of.
Description - Similar to the Image, this is not required, but helps clarify to the customer what this piece of inventory is.
Price - (see here for details on setting Rental Prices).