Several Avery labels are 30 per sheet, 1x 2-5/8 inches. The different numbers represent different pack sizes, colors, materials, adhesives or printer compatibility (inkjet or laser or both), but they all share the same template.
You can design these using the 5160 template in Avery Design & Print Online.
Here's some information on recommended printer settings.
If you want more information about a specific Avery label, search for the product number on avery.com.
Here are other popular address sizes: