Several Avery labels are 20 per sheet, 1x4 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 5161 template in Avery Design & Print Online.
You can also use a template built into Microsoft Word or download an Avery 5161 template for Word, Photoshop, Illustrator, InDesign or Pages.
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.