In your estimate, you can decide whether you'd like your line items to be "option" and whether you'd like the quantity of the line item to be "adjustable".
Optional Line Item
You can specify if your line items are “optional” within your estimate. Use optional items to creatively upsell your prospects and/or give them a “menu” of product options to choose from.
You can also specify if your line item should have an adjustable quantity, which would enable your prospect to choose the quantity that they want. Use this feature to suggest a quantity, while giving your prospects the opportunity to adjust to their desired quantity before accepting. Power to the people!