If you're looking to add a spigot, thermometer or site glass to your kettle, you'll probably need a step bit. Amazon has a Neiko Heavy Duty Titanium Step Bit on Sale for $12.24. That's a 51% discount. Shipping is free with a $25 order.
Neiko Heavy Duty Titanium Step Drill Bit, 7/16 to 1-1/8-Inch by 1/16-Inch Increments - $12.24 (Save 51%) + Free Shipping with $25 order