In a heavy saucepan, combine sugar, corn syrup, & butter. Bring just to a boil over medium heat, stirring constantly. Continue boiling, without stirring, at a moderate-steady rate for 4 minutes. Remove from heat.
Stir in milk and return to heat. Reduce heat to medium/low, cook and stir until candy thermometer reads 245 degrees F (firm ball stage). Keep warm.
Quickly dip pretzels into caramel, allowing excess to drip off. Dry on silicone baking mats or well-buttered baking sheets. Parchment and/or wax paper are NOT recommended.
Pour remaining caramel into greased pan and allow to cool before cutting into squares.
Melt candy coating. Dip in candy coating, and when dry, drizzle with the other flavor of coating. After cooled, store in airtight containers.