Preheat oven to 275°F
In a large bowl, combine Corn Chex, Rice Chex, bagel chips and pretzels. Set aside.
Combine melted butter, worcestershire sauce, garlic powder and salt. Pour mixture over cereal mixture.
Now get your hands dirty. Use your hands to gently toss and evenly coat entire mixture.
Transfer to an ungreased large rimmed baking sheet in an even layer.
Bake for 45 minutes. Stir every 10-15 minutes while baking.
Remove from oven and immediately stir in sweet walnuts.
Let cool then serve or store in an airtight container.