Cubanelle peppers are light green to yellow colored with a sweet and mild flavor. They like an elongated bell pepper. Cubanelle peppers are similar to banana peppers and make an acceptable substitute for recipes calling for Anaheim peppers.
These peppers can be hard to find. There are many online sources for seeds if you'd like to grow your own. Otherwise, look for them in your local farmer's market.
If you don't have cubanelle peppers you can substitute equal amounts of one of these alternatives: