Boss StreuneR (also known as upper Streuner) are a boss version of StreuneR are 4 times stronger. Like the StreuneR, they will fire on passing players. They have a visual difference when compared to the normal StreuneR, in having a slightly bigger alien ship. They can be compared to Boss Mordon but with slightly faster speed. Unlike regular StreuneR, once a Boss StreuneR's shield is down, it will reverse the way your ship flies. This can be annoying when farming multiple Bos StreuneRs.