Preheat an oven to 250 degrees F (120 degrees C). Lightly grease a baking sheet. Arrange pretzels in a single layer baking sheet.
Combine butter, brown sugar, corn syrup, and salt in a large saucepan. Bring to a boil over medium-high heat. Do not stir once the sugar syrup begins to boil.
Heat to 244 degrees F (117 degrees C), or until a small amount of syrup dropped into cold water forms a firm but pliable ball.
Pour hot mixture over pretzels; toss to coat evenly.
Bake pretzels in preheated oven for 10 minutes. Stir; continue to bake until crisp, about 10 minutes.
Remove from oven and break into individual pieces. Cool on wire rack or parchment paper.
