"Kastler" is not a commonly used word, but it can be broken down phonetically as /ˈkæs.lər/. The "k" sound is pronounced as in "kite," while the "a" is pronounced like the short "a" in "cat." Then, the "s" is pronounced as a soft "s" sound, similar to the "s" in "measure." Lastly, the "l" and "r" can be pronounced interchangeably, depending on regional dialect. Overall, the spelling of "kastler" reflects its phonetic makeup.